Well it just gets more bizzare, perhaps am not drinking enough while doing it.
Set-up is in an L shaped room, with an Avant 32 DVD (attached BL2500's), a BS3200 and a BL3500 (in the L shaped bit)
Now I've done the ML readout on the BL3500 and it reads "ML OK" everytime I do a test.
So when I plug them all in together, I can only work the Avant and BL3500. Using the Beo4 remote in the main room pressing RADIO, A.TAPE or CD does nothing. On the BL3500 pressing LINK+RADIO, A.TAPE or CD, the BL3500 display changes clicks on then clicks off again and the BS3200 doesn't even light up.
When I plug in the BS3200 and BL3500 on their own, they work fine though.
I've done the PIN numbers - all correct and happy.
I've double punched the wires, even changed them all and the plug ends too - HELP!!!!!!!! 
What am I doing wrong? 