Excel PDF Printing

It looks like the error is occurring at

Part1Document.InsertPages(0, Part3Document, 0, 1, False) = False

It seems to me that the InsertPages function isn't recognizing Part1Document?

I don't see where OPC was set to a value.

Is there any way to manipulate layers on multiple pages at the same time? i have the same layers with the same names on multiple pages and I don't want to have to toggle them on every page of the document.

I don't have any advice for that. Maybe see a link in: http://lmgtfy.com/?q=VBA+adobe+layers+pdf

Yes, it makes sense that you would need an IF. Otherwise it would be like putting True or False as one line of VBA code which would be a syntax error.