Drop box problem

I've set up a drop box on a shared folder on a server. Users have this share mounted on their client machines (10.4.3) when they log in. On that share I created a drop box. When I look at the folder on the client machine, the permissions appear to be correct. However, when they try to drop a file into the folder they first get an alert that tells them they cannot see the result of the operation and ask if they want to continue (it is a dumb prompt that I need to eliminate eventully but not an issue at this point). The user clicks 'OK' then an error message pops up telling them they do not have sufficient premissions for some of the operations. I have no clue what permissions are needed that they don't already have. Can someone help me figure out why they cannot write to a folder which finder says they have write permission for? TIA.