I've copied your sample code from the Documentation tab and it works fine on the emulator, but if I try to run it on my phone, the below line isn't happy:
WP7BarcodeManager.ScanBarcode(BarcodeResults_Finished); //Provide callback method
The screen on my phone looks like it's trying to fire up the camera, but instantly switches back to the application. In the callback method, the BCResults.ErrorMessage property is 'Error: Photo capture cancelled'... I'm using a HTC HD7, developer unlocked
Any ideas? bBypassCamera is also set to false.