Depth of cut not alawys working

Firstly this may be a problem withe traceing a image.

Im doing names and dates, names always cut ddep enough, but sometimes when the date is cut, its not deep enough, i re do tool path to compensate but no xhange in depth, ive literally added 4mm in 1 mm stages, and no change whatsoever

Could you post your .c2d file and photos of a project which exhibits this problem?