i recently purchased a second hand LG DVD rewriter but came with no cables, i have installed a DVD rewritted before but cant remember how many cables were in the back but im sure it was 3, how many should there be cause with the two i have in just now i am having no luck and i cant write a DVD as you can imagine my time and money is going to waste trying to burn discs! 
You only really need two cables.
One cable comes from the power supply to power your DVD burner.
The second cable is an IDE cable. Which is used to transfer files to and from.
The third cable which isn't neccessary is an audio cable.
The first two are the only ones you need.
Ghostface is totally on the money.
The third cable is only an audio cable for playback of disks.
Maybe it could be that the software you're using isn't suitable for the writer or maybe you're trying to burn the discs to fast for your PC setup.
Try writing at a slow speed, I know it takes long enough at a fast speed but you might find that the PC can't sustain the data rate at the speed you're burning.
I hope this helps.
don't you only need a power and ide cable. Both should already be in the case of your computer unless you have used all open slots on it. I will be installing a new drive in a short while too...
power, ide, and jumper shunt
Digital audio is passed via ide.
If you don't set master/slave correctly you'll have issues. Be sure the device is visible in bios. You might want to experiment with Cable Select
LG isn't very good quality wise. Next time buy Plextor
