I'm assuming you have the aerial going into the box and then out to the TV.
Try reversing this so the aerial goes to the TV and then to the box. This should then give both devices the signal they need.
Try a recording on the box with the TV in standby mode to ensure you can record with the tv off.
The reason I'm suggesting this is that TalkTalk are no longer replacing boxes with a new recordable box, but the lite box that does not record.
Hope it works.
Strange, i thought this was standard on most TVs these days.
All 3 of mine have 2 coax points, one male one female which are "in and out" and these are next to each other.
what make and model is your TV?
Best wait for and OCE to respond re the box if you cant rewire connections.