To answer my own question - the solution was to leave out the adapter cable and plug the unit directly into the OBD port. Now works fine.

Hello, I'm using a iDiagnostics ELM327 adapter purchased recently. The adapter set up ran fine and tests OK under the F9 menu in MultiECUScan 5.0, but I can't get it to connect to the ECU on my Alfa 1.4 Turbo (155 hp version). The lights on the adapter flash when it tries to connect, but I just get ...