Most of my searching seems to show I'm doing what I need to do, but I havent been able to successfully change/customize any of the Notification sounds in the "Push for Gmail" app.

I've gone into the app's folder and changed out a current notification tone for my tone - an .aif file renamed to .caf

Nothing plays for the tone I've swapped, even after respringing.

Is there any kind of common mistake I might be making?