Outputting to DVD Writer

I have a Philips DVDR1640P DVD +/- R/RW/DL capable DVD writer in my HTPC … if I try using CloneDVD to write to the drive then it goes through its paces and goes through a write pass, even says it has completed, but the disc itself is unuseable/unreadable afterwards.

Anyone got any ideas why CloneDVD isn’t actually writing any data to the disc even though it thinks it is? If I use CloneDVD to make an ISO image instead then I can write that to a DVD+/-R using Nero so the drive and the media are OK.