<InputFilepath> or COM

It has been about 8 years since I used to cobble together VB.Net Addins for a Cad program. I am now trying to autosave a pdf file every time the user saves the Cad file both in the same folder. My testing with has not been successful in this program.

So I presume the only alternative is Com. When I go to C:\Program Files\PDFCreator\COM Scripts\VB.Net\COM_TestForm and try to load the solution, I get the error Could not resolve this reference. When I choose Add Reference and go to COM, and select PDFCreator_COM, I get a message … The ActiveXtype library PDFCREATOR.COM.tlb was exported from a .NET assembly and cannot be added as a reference. Add a reference to the .NET assembly instead. But when I look in the .Net tab it isn’t there.

Can anyone help me get started?