I am swapping a SD/DVR settop box from a regular SD settop box. I have connected new RCA audio/video cables from the back of the SD/DVR to the TV (which is quite old & doesnt have fancy connectors as the other TV). Everything is connected fine the SD/DVR powered up BUT....there is no audio or video getting to the TV. The TV is working but nothings happening. Suggestions please? or do i have to return to the plain old regular SD box?