|It sounds you've got the jumper information for the drive in the Promise SuperSwap 1000, and/or possibly the other drive, wrong.|
When two drives are actually jumpered master on the same data cable neither drive is recognized.
You must be confusing a jumper setting for cable select or slave with one for master
The jumper information on the label on the hard drive can be confusing, especially if it's upside down in relation to the back of the drive - if the label shows the relative position of the power connector in relation to the jumpers, go by that.
On optical drives, there are usually markings near the three pairs of pins on the back of the drive, but they may be just imprinted into black plastic and difficult to make out except with good lighting.
Or see the drive manufacturer's jumper information for that drive model.
Different makes and different models of the same make do not necessarily have the same jumper setting arrangement.
Some hard drive models (e.g. some WD) have TWO ways of setting master - one for master by itself (e.g. master single) , the other for master when there is another drive on the same data cable (e.g. master with slave present) - make sure you get that right.
Apparently the Promise SuperSwap 1000 is ATA 133 compatible, so the data cable connection in it has 80 wires and that will work with any hard drive.
All 80 wire data cables have a blue connector on one end - that end MUST go to the mboard!
It is common to un-intentionally damage IDE data cables, especially while removing them - the 80 wire ones are more likely to be damaged. What usually happens is the cable is ripped at either edge and the wires there are either damaged or severed, often right at a connector or under it's cable clamp there, where it's hard to see - if a wire is severed but it's ends are touching, the connection is intermittant, rather than being reliable.
Another common thing is for the data cable to be separated from the connector contacts a bit after you have removed a cable - there should be no gap between the data cable and the connector - if there is press the cable against the connector to eliminate the gap.
80 wire data cables are also easily damaged at either edge if the cable is sharply creased at a fold in the cable.
Try another data cable if in doubt.
That may apply to a short data cable inside the Promise SuperSwap 1000 as well.
If you're going to be removing the drive from the Promise SuperSwap 1000 regularly, the drive in it should be jumpered slave, the other one master, or both drives on the same data cable should be jumpered cable select - that way you don't have to change jumpering when you unplug the drive.
Don't mix cable select and master/slave jumpering for 2 drives on the same data cable - some combinations will work anyway, some will NOT.
If you use cable select jumpering, a single drive is supposed to be on the END connector of the 3 connector data cable - on newer mboards the drive may be detected anyway as slave when by itself and on the middle connector, but on older mboards the drive won't be recognized at all if by itself on the middle connector.