aftermarket rear view camera question

Hi, my 2011 2500 didn't come with the factory back up camera so I installed one of those Roadmaster VR3 cameras. I hardwired the monitor and installed the camera on the license plate bracket and wired it to the backup lights. The monitor doesn't show a very clear photo...there's usually interference lines running up the screen or the picture flickers or jumps. Sometimes it takes awhile to turn on once I put it in reverse. Any ideas? Could this be a truck issue or camera issue? Thanks for any help.