Greek keyboard language greyed out when putting in a city name...

Hi,
I'm using a nüvi 3598.
Normally I'm living in Germany, but now I'm staying in Greece, so I changed the keyboard language to Greek
as well as the country to Greece
Since a few days I'm no more able to put in a city name when I want to use a new destination.
All of the letters are greyed out.
Only a postal code input is possible. I not even can change the country name from Greece to some other name.
When I change the keyboard language to German, everything works fine.

Any ideas?

Thanks