"Invalid Input" when setting .configname

I am writing a batch printing application. It works well in AutoCAD
2002. But in AutoCAD 2000 I get an "Invalid Input" error when setting
the printer using .ConfigName. I know the string I'm passing has a good
value, or at least the value is good for 2002. Here's the code in
question:

With DWGDoc.ActiveLayout
.RefreshPlotDeviceInfo()
'''''''ERROR HERE!!!
.ConfigName = DWGPrinter
.RefreshPlotDeviceInfo()
For Each strPaper As String In
..GetCanonicalMediaNames
If strPaper.ToUpper =
Me.cboPaperSizes.Text.ToUpper Then
.CanonicalMediaName = strPaper
Exit For
End If
Debug.WriteLine(strPaper)
Next
.RefreshPlotDeviceInfo()
End With


Any thoughts as to what could be going wrong?

Thanks.

- Luther