Why can't I add more pupils to a star card?

Why is the add more pupils button showing in a star card? 

Being able to add additional pupils forms part of your User Profile  so you firstly need to speak to the SOLAR administrator at your school to check this feature is turned on.

Once this function has been turned on by your SOLAR administrator then any new star card that has never had data entered into it will display the add more pupils button.

If you open what you believe to be a new star card and the 'Add more pupils' button is not there then click the 'History' button

This will then show you the data which was entered into this star card previously.