GetthumbnailImage VB6

Does anyone know how to call GetthumbnailImage in VB6? I am posting
this here because .NET is where most of the use of GDIPlus is found and
many of you are/were VB6 folks.

I registered the gdiplus.dll and gdipluswrapper.dll and am able to
successfully use many of the GDI+ functions in VB6, but my call to
GetthumbnailImage generates a "Bad DLL calling convention" error.

>From the Object Browser:
Function GetThumbnailImage(thumbWidth As Long, thumbHeight As Long,
callback As Long, callbackData As Long) As GDIPImage
Member of GDIPlusWrapper.GDIPImage

Here is my code from a .bas file

Public Sub gThumb(myImage As GDIPImage)
Dim NewImage As GDIPImage
Dim lWidth As Long
Dim lHeight As Long
Dim lcbd As Long

lcbd = 0
lWidth = 25
lHeight = 30

Set NewImage = myImage.GetThumbnailImage(lWidth, lHeight, AddressOf
MyCallback, lcbd)

End Sub

Private Function MyCallback()

End Function