VB.Net code introducing instability

[ejdavis]

I've written some code to copy wall plan modifiers between walls.  The code work but introduces instability that causes an Unhandled Access Violation later in the session (closing AutoCAD always causes it).  The altered file can be openned without issue after.  How can I prevent the instability?

<CommandMethod("PaintWallPlanMods")> _

PublicSharedSub PaintWallPlanModifiers()

Dim objDB As Database = HostApplicationServices.WorkingDatabase

Dim objEd As Editor= DocumentManager.MdiActiveDocument.Editor

Dim strResults As String = ""

Using trans As Transaction= objDB.TransactionManager.StartTransaction

Try

Dim objSource As Wall = Nothing

Do

Dim peoSource As New PromptEntityOptions(vbCrLf & "Select source wall:")

peoSource.SetRejectMessage(vbCrLf & "Invalid selection.")

peoSource.AddAllowedClass(GetType(Wall), True)

Dim perSource As PromptEntityResult= objEd.GetEntity(peoSource)

If perSource.Status = PromptStatus.Cancel Then strResults = " Canceled at Source Selection." : Exit Try

objSource = perSource.ObjectId.GetObject(OpenMode.ForRead)

If objSource.WallModifierCount > 0 Then Exit Do

Loop

Dim peoTarget As New PromptEntityOptions(vbCrLf & "Select target wall:")

peoTarget.SetRejectMessage(vbCrLf & "Invalid selection.")

peoTarget.AddAllowedClass(GetType(Wall), True)

Dim perTarget As PromptEntityResult= objEd.GetEntity(peoTarget)

If perTarget.Status = PromptStatus.Cancel Then strResults = " Canceled at Target Selection." : Exit Try

Dim objTarget As Wall = perTarget.ObjectId.GetObject(OpenMode.ForRead) 

If objTarget.WallModifierCount > 0 Then strResults = " Wall already has modifiers." : Exit Try

objTarget.UpgradeOpen()

For Each objMod As WallModifier In objSource.WallModifiers

objTarget.WallModifiers.Add(objMod)

Next

Catch

End Try

trans.Commit()

objEd.WriteMessage(vbCrLf & strResults & vbCrLf)

End Using

End Sub

[Gary_J_Orr]

Something is "still open" and trying to do it's thing... Try manually closing your transaction after your "End Using":
trans.Dispose()