Combo drive DVD problem...

[M. Kadioglu]

Hello Group. Just installed a new combo drive in a dual usb ibook. 
First the tray was not staying in unless there is a CD or DVD in it. 
However it was playing DVDs and CDs just fine when loaded. Also 
recorded fine. Like I  said, the only problem was the tray did not stay 
inside when empty. I  opened up the optical drive and discovered that 
some screws were loose, after tightening them the tray started to work 
fine, and the ejection problem went away. However, now it won't 
recognize DVD media, and ejects them after whirring and making attempts 
to read it unsuccessfully. Has anyone had a similar experience? Any 
tips?? Thanks. Matt.