The script is pointing to hudname=objectives, so the ojectives image being displayed is the one you are pointing your script at, you need to find the objectives image this script is telling the system to use. Usually in gamecore/text file
Are you actully trying to display game objectives at this trigger zone or just a message? Because there are a few different scripts you can use..
For displaying objectives using the tab key:
;Objectives on Screen Script
; Script by: Silent Thunder
; Edited by Conjured Entertainment
desc = Display Objectives via TAB key
;Triggers
:state=0:hudreset,hudx=50,hudy=90,hudimagefine=gamecore/huds/objectives.tga,hudname=objectives,hudhide=1,hudmake=display,state=1
:state=1,scancodekeypressed=15:state=2
:state=1:hudunshow=objectives
:state=2:hudshow=objectives,state=1
;End of Script
Also, you could just use a HUD display script instead of the objectives if this is going to cause you problems:
;Artificial Intelligence Script
;Header
desc = My Own HUD
;Triggers
:state=0:hudreset,hudx=50,hudy=90,hudimagefine=languagebank\english\gamecore\text\myownhud.tga,hudname=myownhud,hudhide=1,hudmake=display,state=1
:state=1,plrwithinzone=1:hudshow=myownhud,state=2
:state=2,plrwithinzone=0:hudunshow=myownhud,state=1
;End of Script
You would need to create the image you want displayed and replace the "myownhud" sections of the script to point at the image file you want to you.
Hope this helps!