Mission in FSX "Monsoon Approach"

I tried the mission "monsoon approach", and I have some problems in this mission. (use ILS to land singapore airport)
before landing (B744), heading 050 and alt 2,500 to intercept ILS localizer, after co-pilot told me their is a localizer, I press "NAV" and the a/c turn left to 023 to line up with the runway. few moments later, co-pilot told me that we have intercepted the glide slope, then I press "APP" ("NAV" switch off automatically), a/c slowly decent......but everytime it will "land" in front of the runway.....any thing I done wrong?
thanks
before landing (B744), heading 050 and alt 2,500 to intercept ILS localizer, after co-pilot told me their is a localizer, I press "NAV" and the a/c turn left to 023 to line up with the runway. few moments later, co-pilot told me that we have intercepted the glide slope, then I press "APP" ("NAV" switch off automatically), a/c slowly decent......but everytime it will "land" in front of the runway.....any thing I done wrong?
thanks