[NTLK] Cannot install NCU on Mac OS 9

[r0]

Been trying to test the cables & MessagePad in order to diagnose the 
issue. But I can't manage to make any progress...
I've wasted hours trying to transfer ZTerm to the PowerBook in order to 
link it to the iMac and test the connection, but nothing is happening. 
Nothing is getting transmitted.

Are LocalTalk cables supposed to have a special pinout that makes them 
different from "regular" Mini DIN-8 cables?
Or is it just my lack of skill?

I don't know what to do at all. Does anyone know?
Thanks a lot.