I am unable to get the DVD's I bought to work with my machine.

DVD writable discs are available in 5 "flavours" and you have to make sure that you are using the correct DVD for your machine.

• DVD-R
• DVD+R
• DVD-RW
• DVD+RW
• DVD-RAM

Some machines prefer to use one format over another, although most machines are compatible with most discs (Super-Multi drives actually work with all the formats above).

Check the firmware you have installed as this makes a big difference to the way the discs burn, which you can download from here

Also ensure that you are using the latest version of the software package you use. We recommend you use Nero, due to its ease of use and general robustness, of which a free trial copy can be downloaded off their web site www.nero.com

Another possibility is that certain Japanese makers specifically exclude certain discs.
In the DVD market, some are trying to keep control, and there are a couple of manufacturers who do not agree with it, so they are producing DVD without the approval of the Japanese corporations.
The Japanese corporations therefore decided to block the discs at the firmware level to prevent the sale of cheaper discs, although this isn't the issue it once was.

Link:
www.medea.co.uk/medeasupport/index.php?action=kb&print=35