i know very little about this ! i have a dishnetwork 500 dish with 2 lnbs. very difficult to get 2nd coaxial to receiver. can not get all the channels, is only 1 coaxial the problem ?l

well a little more info would be helpful

what receiver
what actual LNB do you have? Is it 2 LNB's that can be separated or one giant one?
any writing on the LNB? Like DishPro or DIsh Network?

you need a switch.
have yout traced the cables all the way from the dish. they must integrate into a switch somewhere if there are two lnb's on the dish.
you may not need two coax cables to the receiver.
but as iceberg said, we'll need a lot more info.