Philips dvd8701

i have a philips dvd8701 drive on my dell dimension 5150, and it won’t play dvd’s recorded on my panasonic DMR-ES20D dvd recorder. why is this?

What DVDs?
Probably it is DVD-R media recorded in DVD-VR mode, so you would have to install -VR drivers/software.
If it is DVD-RAM, your drive needs to support DVD-RAM and have drivers installed.