how to share win2003 folder in a domain environment

Hi,

I have 2 servers. Server A is win2003 SBS server running active directory and Server B is a Win2003 std server which is part of this domain

I can create domain users in Server A and share folders to the domain users. However in Server B when I create a share folder I am unable to allow domain users to share it. Under permissions I am only able to select local users

What am i doing wrong ? Please help

Thanks