Citroen C4 - Navigation not available on this system

Hi,

I purchased a year old C4 the other day. Its SMEG version is 6.1.D.R20. On pressing the navigation button I get the message "Navigation not available on this system". Is there something I can do to activate the navigation system? My car has the 7 inch touch screen, I was hoping that it has the GPS unit installed and it is a case of me installing or running a mapping update. I appreciate any help that can be offered.

Thanks