Given user ability to give others permissions to her folder on the server

I have a user who needs to be able to set the security permissions of her folder on the server so that she can add and remove others permissions to it.
She already has Full control on the folder and everything that is under the folder. She can get to the folder by going to the server. IE \\servername then drilling down to the folder itself.
How can I find were there may be a denie right. I have been checking the effective permissions of the folders obove hers and I am just not seeing the problem.