if you bought a used blackberry, then the previous user has to release the PIN. this can be done in 2 ways.
1. they log into their BIS and register a new blackberry, which will release the previous PIN.
2. if they don't have another blackberry to register, and are not using the BIS anymore, they must call their carrier and ask them to release the PIN. it's quick and painless, shouldn't take more than 10 minutes.
if the device hasn't been used before, then it's probably RIM related....i'd call rogers in that case as i heard they may have to get rim to manually register your device.