Pioneer DVD Recorder & VCR - DVR-RT501-S

Help! After copying oodles of VHS tapes(family) onto DVD-R, thought I would double check if you can make extra copies of these on your computer. Nothing on my computer recognises a copied DVD by me - Encryptor, Shrink, Nero. So thought I would check if the other DVD players inmy house would play these copies. Admittedly, the two other DVD’s are older (4 years) but they don’t play it either. I’m trying to unravel this problem. I need to copy VHS tapes of my family and want to give them the copied CD’s for their machines and also would like my computer to make extra copies in the future, if ever needed. Thanks.