Field Security Profile - Add User Button not visible

Hi,

I've given full privileges on the Field Security Profile settings to a non Administrator user, but the user is not able to see the 'Add' button under Users in order to Add users to the profile.

The remove users button is visible though and the user is able to go to the User form and add individual user to a Field Security Profile from there.

Any ideas as to what could be the reason of non visibility of the 'Add' button? I've checked the Security Role of the user a number of times and the role has all privileges on Field Security Profile uner Business Management.

Thanks,

Rohit