Custom Addin Error on Re-Load

[Anonymous]

I've been working on an add-in for a bit now and came to a strange issue. My add-in loads and operates as excepted on initial start up, but when I manually unload and the load the add-in I get an error when my code attempts to add my button to the annotate ribbon panel. See my code below:

I read that it could be an issue with an object not being released properly, but I feel like I've gone through and released everything, unless I missed something. When I comment out :

            ' Add a button.
            textPanel.CommandControls.AddButton(m_Button, True)

Everything works fine (except that I can't use the add-in since there is no button created. The error I recieve  is this:

An exception of type 'System.Runtime.InteropServices.COMException' occurred in mscorlib.dll but was not handled in user code

Additional information: Unspecified error (Exception from HRESULT: 0x80004005 (E_FAIL))

Thanks in advance for your time!

Imports Inventor
Imports System.Runtime.InteropServices
Imports Microsoft.Win32

Namespace TBF_Kova
    <ProgIdAttribute("TBF_Kova.StandardAddInServer"),
    GuidAttribute("baa6d8eb-24b9-444d-affa-bb9235933b56")>
    Public Class StandardAddInServer
        Implements Inventor.ApplicationAddInServer

        Private WithEvents m_uiEvents As UserInterfaceEvents = Nothing
        Private WithEvents m_Button As ButtonDefinition = Nothing

        Dim WithEvents m_AppEvents As ApplicationEvents = Nothing
        Dim WithEvents m_DocEvents As DocumentEvents = Nothing




#Region "ApplicationAddInServer Members"

        ' This method is called by Inventor when it loads the AddIn. The AddInSiteObject provides access  
        ' to the Inventor Application object. The FirstTime flag indicates if the AddIn is loaded for
        ' the first time. However, with the introduction of the ribbon this argument is always true.
        Public Sub Activate(ByVal addInSiteObject As Inventor.ApplicationAddInSite, ByVal firstTime As Boolean) Implements Inventor.ApplicationAddInServer.Activate
            ' Initialize AddIn members.
            g_inventorApplication = addInSiteObject.Application

            ' Connect to the user-interface events to handle a ribbon reset.
            m_uiEvents = g_inventorApplication.UserInterfaceManager.UserInterfaceEvents

            m_AppEvents = g_inventorApplication.ApplicationEvents



            ' TODO: Add button definitions.

            ' Sample to illustrate creating a button definition.
            Dim largeIcon As stdole.IPictureDisp = PictureDispConverter.ToIPictureDisp(My.Resources.pencilBig)
            Dim smallIcon As stdole.IPictureDisp = PictureDispConverter.ToIPictureDisp(My.Resources.pencilSmall)
            Dim controlDefs As Inventor.ControlDefinitions = g_inventorApplication.CommandManager.ControlDefinitions
            m_Button = controlDefs.AddButtonDefinition("Title Block" & vbCrLf & "Filler", "TBF", CommandTypesEnum.kShapeEditCmdType, AddInClientID,,, smallIcon, largeIcon)

            ' Add to the user interface, if it's the first time.
            If firstTime Then
                AddToUserInterface()
            End If


        End Sub

        ' This method is called by Inventor when the AddIn is unloaded. The AddIn will be
        ' unloaded either manually by the user or when the Inventor session is terminated.
        Public Sub Deactivate() Implements Inventor.ApplicationAddInServer.Deactivate

            ' TODO:  Add ApplicationAddInServer.Deactivate implementation
            Debug.Print("TBF has been unloaded.")

            ' Release objects.
            m_uiEvents = Nothing
            m_AppEvents = Nothing
            m_DocEvents = Nothing
            m_Button = Nothing
            uiForm = Nothing
            g_inventorApplication = Nothing


            System.GC.Collect()
            System.GC.WaitForPendingFinalizers()
        End Sub

        ' This property is provided to allow the AddIn to expose an API of its own to other 
        ' programs. Typically, this  would be done by implementing the AddIn's API
        ' interface in a class and returning that class object through this property.
        Public ReadOnly Property Automation() As Object Implements Inventor.ApplicationAddInServer.Automation
            Get
                Return Nothing
            End Get
        End Property

        ' Note:this method is now obsolete, you should use the 
        ' ControlDefinition functionality for implementing commands.
        Public Sub ExecuteCommand(ByVal commandID As Integer) Implements Inventor.ApplicationAddInServer.ExecuteCommand
        End Sub

#End Region

#Region "User interface definition"
        ' Sub where the user-interface creation is done.  This is called when
        ' the add-in loaded and also if the user interface is reset.
        Private Sub AddToUserInterface()
            ' This is where you'll add code to add buttons to the ribbon.

            '** Sample to illustrate creating a button on a new panel of the Tools tab of the Part ribbon.

            ' Get the Drawing ribbon.
            Dim drawRibbon As Ribbon = g_inventorApplication.UserInterfaceManager.Ribbons.Item("Drawing")

            ' Get the "Annotate" tab.
            Dim annotateTab As RibbonTab = drawRibbon.RibbonTabs.Item("id_TabAnnotate")

            ' Create a new panel.
            'Dim customPanel As RibbonPanel = toolsTab.RibbonPanels.Add("Kova Engineering", "Kova_Panel", AddInClientID)

            ' Get Annotate Text Panel
            Dim textPanel As RibbonPanel = annotateTab.RibbonPanels.Item("id_PanelD_AnnotateText")


            ' Add a button.
            textPanel.CommandControls.AddButton(m_Button, True)




        End Sub

        Private Sub m_uiEvents_OnResetRibbonInterface(Context As NameValueMap) Handles m_uiEvents.OnResetRibbonInterface
            ' The ribbon was reset, so add back the add-ins user-interface.
            AddToUserInterface()
        End Sub

        ' Sample handler for the button.
        Private Sub m_Button_OnExecute(Context As NameValueMap) Handles m_Button.OnExecute

            If uiForm Is Nothing Then

                uiForm = New Form1()

            End If

            uiForm.Show()
            uiForm.Activate()


        End Sub

        Private Sub m_AppEvents_OnActivateDocument(DocumentObject As _Document, BeforeOrAfter As EventTimingEnum, Context As NameValueMap, ByRef HandlingCode As HandlingCodeEnum) Handles m_AppEvents.OnActivateDocument

            m_DocEvents = g_inventorApplication.ActiveDocument.DocumentEvents


        End Sub

        Private Sub m_DocEvents_OnChange(ReasonsForChange As CommandTypesEnum, BeforeOrAfter As EventTimingEnum, Context As NameValueMap, ByRef HandlingCode As HandlingCodeEnum) Handles m_DocEvents.OnChange


            If BeforeOrAfter = EventTimingEnum.kBefore Then

                Debug.Print("Reason for change - " & Context.Item(1))

            End If


            If ReasonsForChange = CommandTypesEnum.kQueryOnlyCmdType Then

                Dim sheetB As String = ""
                Dim sheetA As String = ""


                If BeforeOrAfter = EventTimingEnum.kBefore Then

                    sheetB = g_inventorApplication.ActiveDocument.ActiveSheet.name

                Else

                    sheetA = g_inventorApplication.ActiveDocument.ActiveSheet.name



                    If sheetA <> sheetB Then

                        'update subjects to be ordered correctly uiForm.method

                    End If

                End If

            End If

        End Sub


#End Region




    End Class



End Namespace


Public Module Globals
    ' Inventor application object.
    Public g_inventorApplication As Inventor.Application = Nothing
    Public uiForm As Form1 = Nothing

#Region "Function to get the add-in client ID."
    ' This function uses reflection to get the GuidAttribute associated with the add-in.
    Public Function AddInClientID() As String
        Dim guid As String = ""
        Try
            Dim t As Type = GetType(TBF_Kova.StandardAddInServer)
            Dim customAttributes() As Object = t.GetCustomAttributes(GetType(GuidAttribute), False)
            Dim guidAttribute As GuidAttribute = CType(customAttributes(0), GuidAttribute)
            guid = "{" + guidAttribute.Value.ToString() + "}"
        Catch
        End Try

        Return guid
    End Function
#End Region

#Region "hWnd Wrapper Class"
    ' This class is used to wrap a Win32 hWnd as a .Net IWind32Window class.
    ' This is primarily used for parenting a dialog to the Inventor window.
    '
    ' For example:
    ' myForm.Show(New WindowWrapper(g_inventorApplication.MainFrameHWND))
    '
    Public Class WindowWrapper
        Implements System.Windows.Forms.IWin32Window
        Public Sub New(ByVal handle As IntPtr)
            _hwnd = handle
        End Sub

        Public ReadOnly Property Handle() As IntPtr _
          Implements System.Windows.Forms.IWin32Window.Handle
            Get
                Return _hwnd
            End Get
        End Property

        Private _hwnd As IntPtr
    End Class
#End Region

#Region "Image Converter"
    ' Class used to convert bitmaps and icons from their .Net native types into
    ' an IPictureDisp object which is what the Inventor API requires. A typical
    ' usage is shown below where MyIcon is a bitmap or icon that's available
    ' as a resource of the project.
    '
    ' Dim smallIcon As stdole.IPictureDisp = PictureDispConverter.ToIPictureDisp(My.Resources.MyIcon)

    Public NotInheritable Class PictureDispConverter
        <DllImport("OleAut32.dll", EntryPoint:="OleCreatePictureIndirect", ExactSpelling:=True, PreserveSig:=False)> _
        Private Shared Function OleCreatePictureIndirect( _
            <MarshalAs(UnmanagedType.AsAny)> ByVal picdesc As Object, _
            ByRef iid As Guid, _
            <MarshalAs(UnmanagedType.Bool)> ByVal fOwn As Boolean) As stdole.IPictureDisp
        End Function

        Shared iPictureDispGuid As Guid = GetType(stdole.IPictureDisp).GUID

        Private NotInheritable Class PICTDESC
            Private Sub New()
            End Sub

            'Picture Types
            Public Const PICTYPE_BITMAP As Short = 1
            Public Const PICTYPE_ICON As Short = 3

            <StructLayout(LayoutKind.Sequential)> _
            Public Class Icon
                Friend cbSizeOfStruct As Integer = Marshal.SizeOf(GetType(PICTDESC.Icon))
                Friend picType As Integer = PICTDESC.PICTYPE_ICON
                Friend hicon As IntPtr = IntPtr.Zero
                Friend unused1 As Integer
                Friend unused2 As Integer

                Friend Sub New(ByVal icon As System.Drawing.Icon)
                    Me.hicon = icon.ToBitmap().GetHicon()
                End Sub
            End Class

            <StructLayout(LayoutKind.Sequential)> _
            Public Class Bitmap
                Friend cbSizeOfStruct As Integer = Marshal.SizeOf(GetType(PICTDESC.Bitmap))
                Friend picType As Integer = PICTDESC.PICTYPE_BITMAP
                Friend hbitmap As IntPtr = IntPtr.Zero
                Friend hpal As IntPtr = IntPtr.Zero
                Friend unused As Integer

                Friend Sub New(ByVal bitmap As System.Drawing.Bitmap)
                    Me.hbitmap = bitmap.GetHbitmap()
                End Sub
            End Class
        End Class

        Public Shared Function ToIPictureDisp(ByVal icon As System.Drawing.Icon) As stdole.IPictureDisp
            Dim pictIcon As New PICTDESC.Icon(icon)
            Return OleCreatePictureIndirect(pictIcon, iPictureDispGuid, True)
        End Function

        Public Shared Function ToIPictureDisp(ByVal bmp As System.Drawing.Bitmap) As stdole.IPictureDisp
            Dim pictBmp As New PICTDESC.Bitmap(bmp)
            Return OleCreatePictureIndirect(pictBmp, iPictureDispGuid, True)
        End Function
    End Class
#End Region

End Module