My tv (an old Toshiba) has one scart, no AV sockets or any other connections. My Pioneer 420HS dvd recorder, vcr & Sky+ box each have 2 scarts.

Prior to moving house, I was able to record from the terrestrial channels & Sky+ to the dvdr without any problems. I used an internal aerial on top of the tv. In my new home, there's a rooftop aerial, which I've plugged into the back of my tv. I didn't have to re-tune the tv & can use videos, Sky+ as well as the terrestrial channels without problems.

However, the problem has arisen with the Pioneer dvdr. I can play dvds or whatever was already stored on the dvdr without any problems, but it won't pick up the channels when I try to tune it through the Setup Navigator, so I can't record anything new. Please can someone advise me on what to do - I've moved scarts around until I've nearly tied myself in knots, but I still can't get it to tune properly. I really want to also be able to copy from the vcr to the Pioneer to copy & eventually get rid of old tapes, but if leaving the vcr out of the setup means the dvdr will work properly then I'll leave it out. Thanks.

The Pioneer (or any recorder) does not "tune" in anything from a scart.
The internal tuner picks up channels via your aerial.
However,if you have Sky+ there seems little point in using an analogue tuner unless you often have to record 3 things at once.
Forget the tuner and remove the RF connection as its not required for either Sky+ or the Pioneer.
Just connect it to the VCR the n straight to the tv while keeping the high quality Scart connection from Sky+ to DVDR to TV.
A simple Scart to Scart connection temporarily connecting the VCR to the DVDR is best.There's no need for a permanent connection ,and it will cut down on spaghetti round the back

Thanks.