Multisession problems

I have an NUtech 082 burner that came with nero 6 OEM. I burned a few files to a DVD-R and then wanted to add some more. Nero recognised it as a multisession (or at least I think it did becuase it showed the files already on the dvd) but when I burned the new session, it just started writing at the beginning of the DVD as if it were a blank one and destroyed everything on it.

I thought upgrading to a newer version of Nero would probably help, but which revision is the best to get? I am currently using whatever version originaly came with the burner.