DVD Writer write only DVD-RW Disks

[equebal]

I have external hp dvd writer dvd300e . This writer is writing only on DVD-RW disks. when write on DVD-R disks it display message "insert blank disk". I changed may disks but problem is still same.
what is the problem?

[Delta]

HP dvd300e supports only write on DVD+RW, DVD+R, CD-R and CD-RW. You Cant even read DVD-R or DVD-RW.

[equebal]

Actually i was not aware about differences in DVD-R and DVD+R.
My disks was DVD+RW and DVD-R that's why it was working only on Rewritable.
Thanks for solving my problem.