DVD Recorder

I have a DVD Recorder,Model #RDR-GXD455.
Sony is the brand. It is six months old. I have tried
to get it to record a program,while I watch another
program. Can not get it to do this. I have pro-
grammed the remote. I have tried a lot of things
to get it to work. NOTHING I tried Sony Chat
with a tech. I think I know more than they do.
And that not saying a lot. So is there a brand
out there that can do this? I would appreciate
any suggestions. Thank You