I think I get it now. In the sim’s planner I guess you have highlighted a navaid at the eastern end of KATL? It’s frequency is listed as 110.50, but you expect 111.30. Right?
I may be wrong, but aren’t ILS antennas typically placed at the far end of the runway?
What happens if you go flying and tune 111.30 when close enough to KATL? It should read IAFA where it reads IDDO now.