Your question is vague. 
  What URL were you trying to mirror?  What other site can't you get pictures
from?   
  Was other site's URL in project Web-addresses?
HTTrack follows links & downloads 

In general: 
  See if Option>>ScanRules allows other site pics
  See if Option>>Limits>>mirror depth is deep enough
  See if Option>>Link>>Get non-html files is on