Permissions related Issue

Hi,

This might be a simple question, but somehow I am not able to figure out what is going wrong.

I have a set of Users that are already added to the Site Collection Administrators group, but when I go to Site Permissions and Check the Permissions for those users, it says "Permission Level None".

I would like to understand when users have been added to the Site Collection Admin Group why does the Permission level say None?

I need help in Understanding it.

Thanks

Vignesh