CD/DVD rom not reading disk

Hi everyone, I have a dell dimension 4700. I have a problem with the CD rom drive. Whenever, i put my disk in the cd rom drive, it seems that runs, since there is a green light that appears when i put the CD in. There is no icon in the MY COMPUTER area stating that there is no CD. What could be the problem. My brother suggested that I put the power thingy in the Select part instead of the slave part. But, i’m not sure if i did put it in the select part. Since, the dell desktop is sooooo hard to unscrew everything.