Can't set up my new Nikkai 5.8GHz video sender.

Question

I have purchased a Nikkai A00HR 5.8GHz Video Sender.I tried to transmit from one room to another without success. I then took the entire set to a portable TV upstairs which runs off a freeview box.I have disconnected the scart cable from my freeview box and from my television and plugged the transmitter into the freeview box and the receiver into my TV. I am unable to get any picture or sound on my TV. I have tried a set-up for a plug and play unit but still cannot get a connection. Both transmitter and receiver are set to the same channel. I have tried it on all 7 channels to no avail.Can you suggest what I am doing wrong?