The reason you are recording a blank screen is because your DVD Recorder is not tuned to your freeview Channels.
Have you connected incoming Aerial lead firstly to DVD then to TV, and linked both by means of 21 pin Scart lead.
Using TV Screen as your guide, go into DVD Set-up Menu and select Auto-tune, and tune in all available Freeview Channels.
My Panasonic automatically tunes in the Channels in the same order as they appear on my TV.
Don't know what Make/Model your DVD is, but you should be able to tune it OK by following tuning instructions in your Handbook.