1. Jumper issues.
All IDE drives require proper master / slave / cable select jumper settings.
Some hard disk drives require a bit more. If connected as a slave, the Master hard disk may well require a jumper setting that says it is a Master in a dual drive configuration. If the Master is Cable select, then as a slave you would have to be Cable Select as well.
On the secondary IDE chain, as you say you are doing, it the drive needs to be set as Master, or if the cable type is the 80 conductor type, it needs to be set for Cable Select using the last connector.
Does this help any? The Web sites for the hard disk manufacturer's have good on-line diagrams of the needed jumper settings if they are not printed on a label on the drive itself.
Finally, it is the case that a drive formatted with one chipset controller type may, may not be readable when used with a controller based on a different chipset.
Most of the hard disk recovery utilities can read the disk in this instance. GetDataBack is well mentioned in this Forum, a test of whether the data can be recovered with a sofware utility can be done (freeware) from this site:
Restorer 2000