Motorola V551 / V330 / V547 / V555 / V557

Hi, i have a v551 and I have used bluetooth to transfer parts of mp3's to it to use as ringtones and it's been working fine until recently. I tried sending an mp3 file to it but when it's done transferring it says "File is Corrupt" and doesn't save it. To make sure it wasn't the file I sent the same file to my sisters phone (she also has a v551) using the same method and it worked and the phone was able to play it. I don't know what to do, can anyone help me out? Thanks.