Quote from:
BlackBerry Code Signing Tips
"So you’ve written the perfect BlackBerry application. It runs great in the device simulator and now you want to run it on a real device. You install it, but it won’t run — because you’re using
controlled APIs. That’s right, a lot of the interesting APIs on the BlackBerry — for example, the persistent store — are protected by a security layer. To get past that layer you have to
sign your application using certificates provided by RIM."