Can't format DVD's with DVDForm utility ("Unsupported disc")

I have an LG DVD Multi Recorder and installed the DVD-RAM Driver software
that came with it. Now, when I try to format DVD's (or CD's for that
matter...) with DVDForm I get the following text in the Drive field: "<E:>
Unsupported disc".
The DVD- or CD-discs are all writable/rewritable discs. However reading
DVD's works perfectly well. In the same PC I also have a "HP CD-Writer 9100
series" that works too, i.e. can write to CD's.
Could somebody please help me with this problem?

.