“Autodesk.AutoCAD.DatabaseServices.Database don't hanve The default attribute,

[sayidyeh]

Hi,I'm doing the program about to copy the unopen DWG file to the active dwg file,I've already see the blog from 

http://through-the-interface.typepad.com/through_the_interface/2006/08/import_blocks_f.html

I use the above code in my program,it success,but all the blocks in the unopen dwg file copy to the new dwg file.it's not what i want. 

so now have the issue 

Here the code:

 Dim acDoc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim acEditor As Editor = acDoc.Editor
        Dim acDatabase As Database = acDoc.Database
        Dim pPtRes As PromptPointResult
        Dim pPtOpts As PromptPointOptions = New PromptPointOptions("")
        Dim FilePath As String = "D:\2RD\PMDS\PMDS\Resources\PFD.dwg"
        Dim FileName As String = " PFD.dwg"
        Dim BlockName As String = "0920101"
        pPtOpts.Message = vbLf & "Insert Point of Block:"
        pPtRes = acEditor.GetPoint(pPtOpts)
        Dim InsertPt As Point3d = pPtRes.Value

        If pPtRes.Status = PromptStatus.Cancel Then
            Exit Sub
        End If
        Using (acDoc.LockDocument)
            Using sourceDb As New Database(False, False)
                sourceDb.ReadDwgFile(FilePath, System.IO.FileShare.Read, True, Nothing)
                sourceDb.CloseInput(True)
                Using trans As Transaction = acDatabase.TransactionManager.StartTransaction
                    Dim acBlockTable As BlockTable = DirectCast(trans.GetObject(acDatabase.BlockTableId, OpenMode.ForWrite), BlockTable)
                    If acBlockTable.Has(BlockName) = True Then
                        Dim Block As BlockReference = New BlockReference(InsertPt, sourceDb(BlockName))
                        Block.ScaleFactors = New Scale3d(1, 1, 1)
                        Block.Rotation = 0
                        Dim ModelSpace As BlockTableRecord = trans.GetObject(acDatabase.CurrentSpaceId, OpenMode.ForWrite)
                        ModelSpace.AppendEntity(Block)

                        trans.AddNewlyCreatedDBObject(Block, True)
                        trans.Commit()
                    Else
                        Dim db As New Database(False, False)
                        db.ReadDwgFile(FilePath, IO.FileShare.Read, False, "")
                        Dim id As ObjectId = sourceDb.Insert(FileName, db, False)

                        If id.IsValid = False Then
                            Exit Sub
                        End If

                        Dim Block As BlockReference = New BlockReference(InsertPt, acBlockTable(BlockName))
                        Block.ScaleFactors = New Scale3d(1, 1, 1)
                        Block.Rotation = 0

                        Dim ModelSpace As BlockTableRecord = trans.GetObject(acDatabase.CurrentSpaceId, OpenMode.ForWrite)
                        ModelSpace.AppendEntity(Block)

                        trans.AddNewlyCreatedDBObject(Block, True)
                        trans.Commit()

                    End If
                End Using
            End Using
        End Using

   Dim Block As BlockReference = New BlockReference(InsertPt, sourceDb(BlockName))    sourceDb in  the sourceDb(BlockName) have the problem that “Autodesk.AutoCAD.DatabaseServices.Database don't hanve the default attribute,and therefore can not be indexed" 

How can i solve the problem with VB.NET ?where the problem ?what should I do ? so thanks!