Good day!

Anyone here had a problem with approach mode? The localizer is armed and aligned but when I click the APP button to arm the approach, nothing is happening, there's no green light that will appear on the button and on the PFD, it is just "LOC", there's no G/S. It is because I didn't set the frequency? I can't seem to find where I can set the frequency for the ILS because the knobs is INOP on pedestal and it looks like that it's automatic just like on an Airbus.