I believe limited accounts need to add the domain in the bottom when logging in. I believe it may be "Default" if you have not changed it.
To get the domain, login with the system admin account, click Admin on the left, and click Domains in the lower left. In the top right you will see the domain(s).
If there are multiple domains they will need an account under each domain you want them to have access to. They will also need to add whatever domain they want to administrator to the domain field when logging in.