Pioneer DVD 115 ROM does not read all dvds

hi

I am new here and still figuring out to see if I can get help.

I have a Pioneer DVD 115 DVD ROM and it does not read all dvds. I have a DVD burner and is connected as Slave to the 2nd IDE and the DVD Rom is primary on the same IDE. The Burner detects and auto plays all DVDs but the ROM does not play all. Can any one show me what to do or look for. Any and all help/suggestions are really appreciated.

I dont know if my drive is defective, but I dont know also that it could be an error in setting it up and not a defect.

Thank you.

Jumper setting comes to mind. Take out both drives, change the jumper to CS (cable select), put the DVD burner on the end of cable as master, and DVD-ROM on the middle as slave.