Optiarc AD-7220S and UDF issue

Hi,
i have the Optiarc AD-7220S and i’m having some problems,
when i burn a dvd using the UDF file system, it’s burning without any errors but when i try to read the disc afterwards then it can’t read it.
i also tried to read the disc in another drive (not Optiarc) and it’s the same, can’t read the disc.
i tried it with two different brands of blank media (one of them is CMC-mag AM3).
i also tried it with nero 6 and nero 8.
tried to burn at X8.
when burning cd’s and dvd’s with ISO file system or even in ISO/UDF there is no problem.
i never had this problem before, i was able to burn with UDF file system without any problem.

could it be that the drive itself is causing the problem?
the drive is 6 months old and still in warranty.