Help Needed on GSA-H20N

Got a HL-DT-ST-DVD-RAM GSA-H20N.

Tried to burn some SONY DVD+RW Ver 1.2/1X-4X but failed.

Even after burning some datas and try to read back on the same dvd rw drive, the drive detected an unformatted media.

It was fine when I burn some CD-R though.

Could anyone help me please?