Code OK in environment but compiled code fails. How to debug or get feedback on a mac? Where is output display() ?

I wrote a program (on a Mac running Yosemite) with GUIDE that works fine in the Matlab 2014b environment but the compiled version has problems. Although the GUI does appear on the screen, most of the functionality fails (pushing buttons don't call the associated code, mouse motion doesn't call the MouseMotion function etc.). The drop down menus respond but their associated functions aren't called.

I'd like to debug this but obviously can't use the environment but even if I go "old school" & sprinkle my code with things like "display('Got to line 100');" I can't see where the output of the display function goes! I tried running the app from the command line using "open myapp.app" but still no text output. I looked in the Matlab console.... nothing!

Help?

TIA,

Dan