I don't believe you need to Push/Pop AppContext in this situation. Normally, in your UIController you need to do
so that calls to Suite functions will work. If you don't do that and try to call into a suite, you should crash. The fact that you're getting an error back from the function suggests that it isn't the problem.
Error number 1146045247 is 'DOC?', which means "No current document." Are you calling it when you don't have a file open? I suppose this could be related to an undefined AppContext, but I'm not sure how it's letting you call suite functions without an AppContext.
For CS6 and above panels, you do need to call Push/PopAppContext( ), but you do it in the Notify Procedure of each panel UI element, not during the creation of the panel.
It works fine now...