I recently exchanged my white blackberry 9700 for the same exact phone. But the thing is, i was able to adjust/change music on my previous blackberry while it was on lock or out of the media screen. After I exchanged it for a new one, I now cannot adjust/change music while my BB is on lock. However, the keys work fine (only when the phone is on the media music screen).

How do I enable the volume adjustment feature (by using the right side volume keys) to adjust volume/change music while the phone is locked?