DVD recorder compatibility?

[cordlessextensioncord]

I recently bought a Toshiba DVR620 VHS DVD recorder and it's great but when I record DVD's they only play back on the Toshiba . They won't play back on a Magnavox DVD player or a PC. Is this because of the machine or the disks being used (I'm using TDK DVD+R's). I don't get it

 

[HarleyDrive]

you have to finalize the DVD to play it on a different player , it's in the menu