The magic eye will normally only work on one caox feed fed directyl from the rf2 output of the sky box. If you have this feed split into two or more feeds it wont work.
Amplifiers and splitters between the rf2 output on your sky box and your remote tv will stop the device from working. There are special sky compatible splitters/amps you can get.
I have also found that some wall plates for tv outlets will block the 9v signal, you should check them out. Open them up, and if you see a pcb and a capacitor in the plate, then I think the plate is part of the problem. You can get cheap ones for a few euro to replace.
First thing to do, is plug your magic eye straigh into the back of your sky rf2 output and make sure the led lights up.
Following that, confirm how your cable is fed back up to the remote tv/tv's. If you can, ensure that the rf2 output is fed to only one remote TV.
Go to remote TV point and plug remote eye in, checking for the led again.
If no led lights up, then chack faceplates connectors etc.
You could look at one of these also
http://www.oneforall-int.com/?pag=39&prodnr=101
Dont go for the digisender if you can do it wired!!