New TTR2 song downloads don't work, though the old ones do.

Let me start by saying you guys are the best. TTR2 is by far my favorite game on my iPhone. Question is this, why do none of the new tracks that I download from TTR2 work? I've tried downloading the new Coldplay songs, the Owl City Song, the Dashboard Confessional Songs,.. none of them work. They load but never play. Please help! Keep up the good work!!