Problem with voice activaction for sat nav COMAND

[Munk53]

I have a Mecedes C-Class on a 19 plate and I am having a problem with the voice activation on my sat nav.

The sat nav works whan inputted manually but not via voice control.

Each time I get the massage " I am unable to connect, please try later."

All other functions in COMAND are unaffected.

Any ideas please.