I have 10 ft cm dish ,c238 lnb ,2x4 multi switch ,trying to hook up 3 receivers,I can hookup 2 receivers straight to lnb ,both work,disconnect 1 receiver and hook up 3rd receiver and it works ,that tells me my coax is ok ,now trouble starts when installing 2x4 multi switch I get no signals ,have tried 2 different multi switches with same no signal ,what am I missing ?