Premium Family Invitations

[user-removed]

Hello,

I have a question to the Premium Family Account. I upgraded my Premium to the Family Premium Account that my family and me can save money. So I invited my parents and everything worked out as it should. I also invited my sister and she got the invitation, filled in her address and wanted to submit. But everytime she pressed the button there was a error message that she can´t use the Premium Family Account. 

What can I do now? What´s the problem? 

We tried so many times, made a new account for her, tried it on many smartphones and Laptops....... I don´t know what do do anymore!

I am very hopeful that someone can help us!

Thank you!!!