I have and Elation Pro OP that I set-up on one channel to control a pair of colorstrips. On other channel a pair of color palette's. I set each pair up on different scenes. Now when I switch from one to the other , it blacks out the pair that I switched to. Have correct cables and even tried a terminator. I had bought this unit on Ebay from centerstagelighting. It was a B-stock item. Is this the way the Op Pro works or is it a defective unit?