Cannot access Shared Folder on a mac to Windows File Server

I have a file server running server 2003, ive created a new shared directory and configured File Server for MAcintosh (through computer management on the server). Ive added the individuals that use macs to the security and permissions for this directory. Using smb://servername, they can see the directory and access files, but cannot save, move, rename files within that directory. The error reads:
The item “filename” could not be moved because SHARED DIRECTORY cannot be modified.
I can drag a file out but cannot write it back to the shared folder.
Ive checked their permissions back and forth im not real sure what to try next.. any suggestions?