Master and slave drive will not work on primary ide cable

Hello Guys—When I try to hook up a slave drive with the master drive on the same primary ide cable neither drive will work,at boot up, message says there is no hard drive—I then hooked up the slave drive on the secondary ide channel with the cd optical drive and every thing works–can any one tell me what I am doing wrong???–I have checked all the connections on drive end and on motherboard—Pulled cables out and reinserted them to no avai.
Windows98 SE
Master hard drive seagate about 4.3 g…
Second hard drive seagate --20 gb…
Thanks Delbert
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Try using the cable select option instead of explicitly setting them. The master/slave will then be determined by the drive’s position on the IDE cable.

Hello KING ADDIS:
I am very sorry about being so late replying to your solution to my problem,I had business out of state and just got back and hooked the hard drives up cable select and it worked,you sure know computers—Thanks a million—DELBERT