Hello there...I have a question and a problem at the same time.

I usually buy songs on iTunes/ iStore and when I want to set this particular song I bought as a ringtone on my BlackBerry Curve, it actually does not work out and the normal retro ringtone *ringring* comes up and not the song I used to choose. And it is always that way with songs I bought in the iTunes store. can someone tell me, how I could solve this problem?

thank you very much,
regards.