I changed only the HUD file and location and assigned it to a characters AI Main to test and it worked fine. Maybe it's your HUD location? This is what I used:
;Header
desc = game conversation show one screen once only no sound
;Triggers
:state=0:hudreset,hudx=50,hudy=50,hudimagefine=gamecore\text\lockeddoor.tga,hudname=img1,hudhide=1,hudmake=display,state=10
:state=10,plrdistwithin=160:rotatetoplr
:state=10,plrdistwithin=60:rotatetoplr,state=20
:state=20,plrdistwithin=60:rotatetoplr,hudshow=img1,hudfadeout=img1
:state=20,plrdistwithin=60,plrusingaction=1:state=40
:state=20,plrdistfurther=60:state=40
;End of Script
Best.
I'm sorry, my answers are limited. You must ask the right question.