Showing sheets and forms, not running macros, from add in

Follow up from this post regarding usage of an add in for distribution purposes:

I now have the spreadsheet I want to distribute saved as an add in stored in a network repository. RoyUK has provided me with some links with code I lifted to add custom menu items. The last problem I have is that I'm not trying to call a macro, but am instead trying to load the sheets (there are 4 sheets) and forms (there are 7 forms).

With what I have now, I can launch a macro with no problem, but cannot get the sheets / forms displayed to the user. I've tried launching a form by loading / showing it, but I get error message (runtime error 9).

Any idea how I can get my sheets to load?