Need Help With NEC ND 3530A

ok first of all i have a dell dimension 8400 computer which comes with an NEC ND 3530A optical drive. recently i just bought some verbatim dvd+r double layer media. i burnt a disc successfully and tried it out. the disc could work. however a few hours later i put the disc into the drive but the dvd could not be read. the drive just shows that i have not put in any disc. i have tried many things like flashing the firmware using liggy’s 3.01 fw but i still have the problem. when i put the dvd into my laptop, the dvd could be read. so i am not sure if my drive is damaged or something. anyways, my drive is still able to burn and read dvds single layer and cds. can anyone help me out? appreciate it.