If the Panasonic ram disc is brand new, and totally clean (free of smudge marks, no scratches), than it should work. If you have tried over and over again with the same result, than there is definitely something wrong with the recorder.
I hope you returned the unit in time to get your money back. If not, raise a stink and ask for managers until they give you the money back.
By the way, I personally use a brand of dvd-r called "Taiyo Yuden". I buy them at Supermediastore or shop4tech. The brand is supposed to be the creator of cd-r's. They are top quality. If you research it you'll find out that a lot of times different brands actually use different manufacturers. Sometimes one brand can actually use two different manufacturers. Usually the quality from these brands are Medium. The one exception is Verbatim which I think actually uses Taiyo Yuden discs. It's often cheaper to buy the Taiyo Yudens from one of those two stores than it it to buy a brand at an actual store.