Problem with referrals

I'm at the first level
And there is more than one person
You send invitations to them
But there are some people involved through me and not being added in referrals (strength in numbers)
A simple example
I was there I have so
11/15
The sense that I invited 11 people from 15 must invite them
I invited more than 3 people afterwards and participate in the game
And show already in the Friends bar below
But not being added in the list that should thus be made with 15 invited
I ask you to clarify the problem