Is this from std AC9 (or std AC9 SE) lib or 3rd party object?
You need to load missed file. But 1st you need to know wich one. In case when you load separate objects (means not full lib.).
To find missed file name (if it's not appears in Warning Dialog) open windowsilltrim.gsm and goto line 560. If cann't read scripts just copy/paste line 560 into this post. Maybe we find any solution