Fiat Stilo 2003 192 Brake Lights Defect

Hello.

I have a problem on a Stilo 2003 SW, in board computer always appears brake light defect, i already changed the bulbs, and the lamp holder but the message appears, then i changed the brake light switch, again the same fault, in ABS i get message CAN BUS cluster defect.
Any idea what i can check?
BTW the 3 brake light are all working ok, but the message is still there!!!

Thanks a lot!