Dvd+r burned on NEC 2500 - Error on Philips dvdr70

I try to make a backup copy of a dvd. I used DVDDecrypter, DVD Shrink and CopyToDVD to make a copy of the dvd on a DVD+R disk using a NEC ND2500-A drive.

I can read this disk on my PC and on a Scott DVD player. However, if I try to play it on a Philps DVDR70 I just get the message “disk contains invalid data”. I tried two different brands of DVD+Rs. If I do exactly the same thing with a DVD+RW, this disk works in the Philips player.

Any ideas?