Нестабильно грузится AutoCAD 2012 из внешней программы на VB.NET

Private Sub CallProgDWG()

        Dim acadApp As Autodesk.AutoCAD.Interop.AcadApplication
        Dim StrCommand, FullNameFileDWG, NameFileDWG As String
        FullNameFileDWG = mass_dwg(0)
        NameFileDWG = System.IO.Path.GetFileName(FullNameFileDWG)
        MyPrinterLISP = Replace(MyPrinter, "\", "\\")
        StrCommand = "(load " & Chr(34) & "plot.vlx" & Chr(34) & ") (plotexe t(list " & Chr(34) & UCase(MyPrinterLISP) & Chr(34) & " nil nil " & Chr(34) & UCase(NameFileDWG) & Chr(34) & " " & Chr(34) & MyStyle & Chr(34) & " t)) "

        On Error Resume Next

        acadApp = GetObject(, "AutoCAD.Application.18")
        If Err.Number > 0 Then
            Err.Clear()
            acadApp = CreateObject("AutoCAD.Application.18")
            If Err.Number > 0 Then
                MsgBox(Err.Description)
                Exit Sub
            End If
        End If
        acadApp.Visible = True

        While (acadApp.GetAcadState().IsQuiescent <> True)
            Thread.Sleep(100)
        End While

        acadApp.Documents.Open(FullNameFileDWG)
        acadApp.ActiveDocument.SendCommand(StrCommand)


    End Sub

On Error Resume Next 

        acadApp = GetObject(, "AutoCAD.Application.18") 
        If Err.Number > 0 Then 
            Err.Clear() 
            acadApp = CreateObject("AutoCAD.Application.18") 
            If Err.Number > 0 Then 
                MsgBox(Err.Description) 
                Exit Sub 
            End If 
        End If 

        Call WaitIdle() 
        acadApp.Visible = True 
        Call WaitIdle() 
        acadApp.Documents.Open(FullNameFileDWG) 
        Call WaitIdle() 
        acadApp.ActiveDocument.SendCommand(StrCommand) 

        acadApp = Nothing

  Private Sub WaitIdle() 
        While (acadApp.GetAcadState().IsQuiescent <> True) 
            Thread.Sleep(100) 
        End While 
    End Sub