Open Directory Changing the Dock

Hi, I am trying to change the dock icons for a user (student). The icons i add to OD Dock prefs are added to the users dock no worries, but the icons i dont want on the dock aren't removed. I have not selected Merge with users dock. and i am pushing a Group Folder to the dock as well. which also appears no problems. Do i have to change some default profile setting somewhere?? Any help would be much appreciated. Regards Don