Righteo, the first ting you should avoid doing in this situation, is what millions of people would do when they eithe have little or no TV signal, what they do is to rush out and buy a signal booster. Now this is very wrong, as the signal is not improved as such. Any distortion or "noise" is also amplified with a booster, so this is a futile effort. What you are probably best off doing, if you have a digital aerial is (if you are going to add a booster) is to attach the thing as close to the aerial antenna as possible (up to about 500mm from the aerial base where the coax cable joins the mast).
Now if your TV is still not working, then i reckon that you should investigate the box that both your TV sets are connected to. This includes all of the cabling too. It might be well worth checking that both of your TV sets have SCART connections to the cable box, and that there are enough channels to both TVs from the box, (ideally there should be two or three SCART connections on the box) if not, then you can use a SCART adapter, but you may loose picture quality on one of the TV's.
Once you have set all the wiring and cabling in plce, it is time to pair the TV to the signal that you want to recieve. Now your user manual will tell you on how to scan and save the channels to your TV set, or for freeview, sky, NTL and cable, then all you need to do is ensure that your TV is tuned into the box (in your case it will be the cable box). Now setting this to the AV1 channel will be best (just as long as you have good SCART) or you can run your TV's tuning setting through the coaxial 75ohm cable in order to pickup the signal that way. SCART is prefffered though as it gives better picture ratio, quality and is faster to tune.
Now, should all of this not work, then i recommend getting hold of your manufacturers/ vendored model of device.now i you hit up http://www.google.co.uk
and type in your device builder ollowed by the words "manual, user guide or technical specifications" then you should return a whole bunch of eye candyishresults or you to read and understand.
Should you still have a problem, then you can always get hold of me here and I will be more than glad to help.
In the meantime, i hope that this is the fixya for you.
All regards, and best o luck on this one