I've put together some Python code and created a Python Add-in toolbar & button which allows me to run a report on a selected feature and immediately opens the report as a PDF. I have it working perfectly. The problem is that it only works perfectly in one specific MXD. When I attempt to use it in another MXD, or install it on another computer, the button does not work (the button's icon does not even display). The button also does not work on another computer when I use the MXD that works on my computer. Since the button is working in one MXD, I suspect that the problem does not have anything to do with the code itself, but with the add-in wizard? I'll attach the code anyway.