Armed for ILS capture with AP engaged (aileron/elevator) and altitude hold set to "on".  Change AP to Nav to capture localizer.  It does so but only after I disengage the HDG hold (should do so automatically).  When established I set AP to AutoILS (Manual ILS setting used in Youtube video but on v2.7 it disconnects the altitude hold as it should) Glide slope appears on the ADI but sometimes stays orange on annunciator.  But even if it is green, the aircraft fails to follow the GS.  I must do so manually or it stays at selected altitude.  Throttle control seems to have too much delay but i usually manage to get speed down to Vref+10 with Flaps 25 and Gear down as GS beam becomes active.  Still the aircraft refuses to follow the GS.  I have read the manuals and have a copy of the real 727 FCOM which Captain Sim has wonderfully simulated in almost all regards.  But AP seems not to be responding as it should.  Any suggestions?

Craig