Hi Guys,

I'm in the process of writing a .NET app that shows a preview image of the drawing sheets for a selected file. I am using the code below which I got from here: 2017 SOLIDWORKS API Help - Get Preview Bitmaps of Drawing Sheets Example (VB.NET) and here: 2017 SOLIDWORKS API Help - Get PNG Preview Bitmap and Stream for Configuration Example (VB.NET). The issue I am having I will get blank sheets previews for some sheets but not others. Any help or advice is appreciated.

    Public Function SheetImages(SelectionName As String) As Image
        Dim swClassFact As SwDMClassFactory
        Dim swDocMgr As ISwDMApplication
        Dim swDoc As SwDMDocument10
        Dim sDocFileName As String = BrowseTB.Text
        Dim nDocType As SwDmDocumentType
        Dim nRetVal As SwDmDocumentOpenError
        Dim sLicenseKey As String = My.Settings.swDocMgrKey
        Dim swCfgMgr As SwDMConfigurationMgr
        Dim vCfgNameArr As Object
        Dim vCfgName As Object
        Dim swCfg As SwDMConfiguration7
        swClassFact = CreateObject("SwDocumentMgr.SwDMClassFactory")
        swDocMgr = swClassFact.GetApplication(sLicenseKey)
        If InStr(LCase(sDocFileName), "sldprt") > 0 Then
            nDocType = SwDmDocumentType.swDmDocumentPart
        ElseIf InStr(LCase(sDocFileName), "sldasm") > 0 Then
            nDocType = SwDmDocumentType.swDmDocumentAssembly
        ElseIf InStr(LCase(sDocFileName), "slddrw") > 0 Then
            nDocType = SwDmDocumentType.swDmDocumentDrawing
        Else
            nDocType = SwDmDocumentType.swDmDocumentUnknown
            Return Nothing
            Exit Function
        End If
        If nDocType = SwDmDocumentType.swDmDocumentDrawing Then
            swDoc = swDocMgr.GetDocument(sDocFileName, nDocType, True, nRetVal)
            If (swDoc Is Nothing) Then
                MsgBox("Unable to open document.")
            End If
            Dim Sheets As Object
            Dim Sheet As SwDMSheet2
            Dim nError As Integer
            Sheets = swDoc.GetSheets
            Dim nbrSheets As Integer
            nbrSheets = CLng(UBound(Sheets)) + 1
            Dim snbrSheets As String = Convert.ToString(nbrSheets)
            Dim i As Integer
            For i = 0 To UBound(Sheets)
                Sheet = Sheets(i)
                If Sheet.Name = SelectionName Then
                    Dim objBitMap As Object = Sheet.GetPreviewPNGBitmap(nError)
                    If nError = 0 Then
                        Dim imgPreview As System.Drawing.Image = PictureDispConverter.Convert(objBitMap)
                        Return imgPreview
                        imgPreview.Dispose()
                        Exit Function
                    Else
                        Select Case nError
                            Case 2
                                MsgBox("Error: No preview data stored with document.")
                            Case 4
                                MsgBox("Error: Failed to make the bitmap.")
                        End Select
                    End If
                End If
            Next
            swDoc.CloseDoc()
        ElseIf nDocType = SwDmDocumentType.swDmDocumentAssembly Or nDocType = SwDmDocumentType.swDmDocumentPart Then
            swDoc = swDocMgr.GetDocument(sDocFileName, nDocType, True, nRetVal)
            swCfgMgr = swDoc.ConfigurationManager
            vCfgNameArr = swCfgMgr.GetConfigurationNames
            For Each vCfgName In vCfgNameArr
                If vCfgName = SelectionName Then
                    swCfg = swCfgMgr.GetConfigurationByName(vCfgName)
                    Dim objBitMap As Object = swCfg.GetPreviewBitmap(nRetVal)
                    Dim imgPreview As System.Drawing.Image = PictureDispConverter.Convert(objBitMap)
                    Return imgPreview
                    imgPreview.Dispose()
                    Exit Function
                End If
            Next
            swDoc.CloseDoc()
        Else
            Return Nothing
            Exit Function
        End If
        Return Nothing
    End Function

Public Class PictureDispConverter
    Inherits AxHost
    Public Sub New()
        MyBase.New("56174C86-1546-4778-8EE6-B6AC606875E7")
    End Sub
    Public Shared Function Convert(ByVal objIDispImage As Object) As System.Drawing.Image
        Dim objPicture As Image
        objPicture = GetPictureFromIPicture(objIDispImage)
        Return objPicture
    End Function
End Class