This is step by step the way I did it and I had no problem

On final
Autopilot on
Autothrottle on
Alt. hold
1) Make sure GPS/NAV switch is in NAV pos. and ILS switch is lit.
2)Tune NAV1 radio to ILS freq.
3)Set runway course.
4)About 2000-2500 ft above ground level to intercept glide slope......when the glide
slope is intercepted, Alt. hold will disengage by itself to allow the plane to follow the slope.
5)Check gear, flaps, auto throttle set to final approach speed.
6)Fly straight into ILS feather and push the APR (approach hold) button.
7)Sit back and monitor......take over at decision height and land the plane.

If you're doing this and you still have problems........try redownload/reinstall :-/
Hope this helps
Chuck