TNS510: RDS-TMC button not turning green colour

I have a TNS510 navigation system on my car, which has an RDS-TMC traffic information feature.
I'm noticing that the TMC button on the main screen is not turning 'green', which means that the system is not activated, although I do notice traffic-jam icons on the road maps.
TMC FM radio channels are set properly.

Any idea what could solve this ?

Where can I find firmware info on the TNS510 ? Want to check if the latesrt firmware is installed. SDcard with map is fine.

Thanks,
V.