Samsung Exclaim txt volume problems.?

I got the Samsung Exclaim through Sprint. I downloaded a couple ringtones from Phonezoo. When I set one of them for the txt alert it works for a little bit then it will just quit working and only vibrate. I called Sprint and they said the phone doesn't support MP3 ringtones, well if it didn't then why can I use a ringtone for when someone calls me, and it works everytime someone calls. Does anyone know what is wrong, or how I can fix it?
 
Back
Top