Samsung Brightside Ringtones?

Hi, I was wondering how to transfer clips of songs to my phone. I created a 40 second ring tone using Garage Band and copied it into my phone's "My Sounds" folder. When I went to Media Center--My Sounds after disconnecting my phone, the ring tone didn't transfer. Did I do something wrong or miss a step?
Thanks
I think the file format may be wrong. What should it be changed to? One is at m4a & the other is at m4r (if that means anything).
Edit- Fixed it. The file format/extension should be mp3.
It is now showing up on my phone, but there is no sound. Help? :(