Daniele -- looking at the picture of your IDE cable, I did the exact same retarded thing as you. (It's OK, we all have these moments sometime in life. In my case, I had a big fat Spaten Optimator and decided it would be "fun" to re-arrange the inside of my miggy a bit nicer. Bad idea!)
Fortunately, I flipped mine off quick enough and avoided damage to the IDE-Fix Express board (still operates 100% reliable, 5.0 mb/sec raw read with an overclocked Apollo 1260!).
Afterward, I had similar strange symptoms (IDE not working with Express adapter connected).
After repairing the broken trace underneath (around the IDE port area IIRC) it's worked flawless ever since.
Hope you get it working!