OpenSUSE :: Adding User To Access Control List In Nautilus

I have a shared folder that has it's access restricted to certain users on a file server at work. Currently when I try to add a user I follow this process:
Right click the Folder, go to Properties
Click the "Access Control List" tab
Select a user from the "Participants List"
Click Add

For most users this process works fine but with one of them I get the following error:
"Could not add ACL entry: Invalid Argument"
I also tried a script that a former employee created which seems to employ this command:
setfacl -m u:<USER>:rw- <PATH>
Running the command with the correct user and path returns a similar "Invalid Argument" error.
We're using OpenSuse 10.2.