Finally received all the parts to finish the installation on my HB 798. It has the side imaging transducer on transom with shoot thru and y cable. Before hooking up the shoot thru and y cable, when in shop (no water) the screen would still show a scrolling while in side imaging mode. Now that both the side imaging and shoot thru are hooked up it does not scroll while on the SI screen. Just a black screen. Should I be concerned or just wait until I can actually get it out on the lake? Just seems weird that it would scroll before like it was scanning but not now.