EFIS

Can someone please help a relative newcomer? I have tried, without success, to activate EFIS. When I select the EFIS Master Switch, Type, Range, Density and Plot Intercepting Path all become active. The remaining buttons - Lock to ILS etc; Lock to VOR etc; VOR 1; VOR 2 and Altitude - all remain Inactive. Probably there is something I am missing but I cannot think of it. Any assistance would be appreciated. 
