Copied DVD-R

I recently copied several old VHS homemade tapes to DVD-R (from Memorex) using a 3 year old Sony combo DVD & VHS player. When I try to play on a Toshiba HD DVD player they will not play. What can I do?

Please relate the process used, start to finish & if what you burned with produces a burn log, post it. Leave nothing out.

Thanks for follow-up.
There was no burn log generated. I put in a blank DVD-R & then the VHS tape. There is an arrow button to copy from VHS to DVD which I pressed. The DVD plays on the older Sony unit but not on the Toshiba HD DVD.

Possibly a media issue (ie: incompatibility with the Toshiba). Try a different brand/type of media.