I've had issues with the Snap 5x1 switchers recently.  If I connect a device to input 1 on them, I get no picture.  If I move the device to input 5, that usually clears things up.  This usually happens with DirecTV receivers, but I've had it happen to a couple DVD players as well.  It basically turns it into a 4x1 since I can't trust the first port.  I need to find a new brand to use.