Can't issue MDI command when not homed

I have recently had to return to 2.7.15 from 2.9.4.  (There is no easy way to upgrade from 2.7.15 to 2.8 which is required to get to 2.9.4.  Attempts to install from 2.9.4 ISO were unsucessful.  Even getting 2.7.15 to install from ISO was hard,) 

This all worked fine in 2.9.4.  In axis gui, I have homed all four axes.  Z=0.  When I use G1 Z1 f4, I get "Can't issue MDI command when not homed."  Can you tell me what I need to fix?

Fixed.