I could never get it to work with a dual hard drive cable as slave master set up.
They don't allow ANY other device to be recognized on the same bus...a total PITA, but it's unavoidable with a single cable setup.
I've tested maybe 5 different versions, all with the same problem you report.
Best just to grab a cheap buffered 4-way interface & be happy with a total of 3 IDE devices (or 2 fixed & 2 switchable if you get tricky ;-) ).
PZ.