Sony DW-Q520A

ive recently bought the DW-Q520A burner for my advent 7039 laptop, it had a cd burner in it that could play dvd. when i changed it over it doesnt recognise blank dvds and its having problems playing dvds, its still reading game disks though. ive read some of the other posts and checked what they said, both my drives were already DMA enabled. i dont know what to do next really, any help is appreciated in advance
ozon