HELP my dvdrw combo drive wont recognize cd-r

[Nerdgunner]

Its actually an image i downloaded .iso I tried burning other things though on a cdr and it still wont recognize it. Theyre memorex CD-r and they say music on them but theyre just regular 700mb cd-r. I also tried a standard cd-r and it said the same thing. Its either the burner itself or the software. I was using Roxio 7.5, and a writemaster dvdrw drive. It says compact disc rewriteable ultra speed+ on the damn drive though.