I don't know exactly how you have connected everything, but I would suggest you have to record AV1, AV2, EXT1 or EXT2, while the hard drive is playing.
This means setting the dvd recorder up manually and choosing AV1 (or whichever is the relevant one) as the channel and playing the hard drive.
Try turning the dvd on so you are watching tv through that - when you change channel on the dvd the channel on the tv changes.
Now turn your hard drive on to play - and change channel on the dvd until you see the hard drive on your tv screen - either by pressing the AV button repeatedly, or changing the channel down from zero.
When you get the right picture on the tv screen, you will know which channel to record.
Hope this makes sense.