I chained 2 null-modem adapters to be able to plug anything in and that combination probably doesn't pass all nine wires.b

The fact you had to do this does imply the sled is/was wired incorrectly - you should be able to use a straight through cable. Some null modems are 3 wire only which could be the case for one of yours.
_________________________
Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)