What directory did you put the file in?
It should be in the assets/media directory. The media directory is the default one for Tier 1 for all files.
Also, make sure that the file name of the file and how you are opening it are exactly the same. Android is case sensitive. This doesn't appear when broadcasting, only when running on the actual device.
It doesn't hurt to add "/media/" to the start of the file name strings for anything that you access in the media directory. That way the app knows exactly where to go.
If your app overwrites the file at some point, it will not overwrite the one in the media directory. It will create a file in the app specific sandbox area (in a directory named media). And any subsequent reads for the same file name will be from the sandboxed file, not from the one in the original media directory.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master