Are you using pixel movement? When I set mine to zero, I was able to use the enemy's (x,y) values to trigger events at certain (x,y) positions. But when I changed it to a one, the enemy couldn't trigger it--this is due to the enemy's coordinates being (10,20) and not logical (5,10).
If you are not using pixel movement, then I have no idea why your enemy is not triggering the events.