Why do I get the error "Camera failed?"

Why do I get the error "Camera failed?"

I replaced the zoom/lens assembly on this Samsung Galaxy Camera 2 EK-GC200. Now whenever the camera app opens, the zoom extends, and the camera buttons come up on the screen, but the rest of the screen stays dark. The a box pops up that says "Warning Camera failed." I have done a factory reset and bought another zoom/lens assembly replacement, but it still gives me that same error. What can I do?