This makes me think you're looking for a string like `'/UICatalog.app'`, but I don't see in your description an example that starts this way. It looks like you're expecting a string like `'/Applications/UICatalog.app'`? I'm confused. I actually think looking for `'/UICatalog.app'` makes more sense, but the docs say `'/Applications/UICatalog.app'` (well actually it's missing a leading `/` in one example too).