Feko Error 20029 after running

I am learning feko manually
i simulated horn antenna like what had been explained in feko demo and after running i get error 20029 that feko cannot find executable file prefeko.exe and my friend has the same error whith another simulation.
Please Can somone help me?
Pleazeeeeeeeeeeeeeeeee.

you cannot simulate feko demo version if segmentation number over 300
you should use licensed version of feko