problems with user permissions and shared folders

I am working on setting up shared folders.

I have a problem where i grant a user permissions to a folder, for full access, and then force those permissions to all child objects.

then when that user tries to save a file or make a folder, they get a permissions denied error.

then can open all the files.

i am not sure what it can be, since i have tried applying the permissions multiple times.

thanks,.