Here is a link to the installation guide for your Pioneer model - refer to every bit of information on p. 29 (which will refer you to some pertinent info in Ch.1): http://www.pioneerelectronics.com/pio/pe/images/portal/cit_11221/98391312Installation%20Guide%20DVR-810HS.pdf
If it will not permit you to do the recording:
You have to use a backdoor method. Inspect your TV and see if it has a yellow jack labelled video OUT or monitor OUT - many TV's do not have them. If you are one of the lucky ones that has a video OUT:
1) Connect a VCR to one of the televisions inputs.
2) Connect a red, white and yellow cable from the video and audio OUTs of your TV to either INPUT 1 or 2 on your DVD recorder
3) Make sure that your DVD recorder is set to either INPUT 1 or INPUT 2 - reading the manual for that model is driving me up the wall - I would change the channel on the DVD Recorder (not the TV) to 2 and use the channel down button until it says Input 1 or Input 2 - whichever the appropriate choice is
4) Play the VHS tape and make sure that you can see the picture on your television screen.
5) Press Record on the DVD recorder
Good luck- I would go insane trying to use that Pioneer - it is user-friendly, but not techie-friendly.
-Tha Mp3 Doctor