"AIMoveTo" doesn't work with narrow entrance ??

I got two same characters . One is playerCharacter I controll; the other on is NPC that should follow me .
The following keeps working until I enter a narrow entrance of a room .
The width of entrance is 80 . The radius of character’s capsule is 34.
I can control my character enter the room. but the npc following me can’t enter.
I trigger the follow event , buti it doesn’t work.
However , if I expand the entrance and its width add to 150 , the NPC can enter!!!
I don’t want to change the entrance’s size…