Find my friends notify button couldn't be clicked

Ok so me and my girlfriend have the iPhone 5 so obviously everything is up to date on ios6.

I set up find my friends on both our phones at the same time in the same way

She can find me and when she clicks on me she can use notify me without any problems.

I can also find her location without problems but when I go to set up notify me the button is greyed out and I can't click it

I tried to use it with one of my friends and I could use notify me with him without any problems!

Both my phone and hers are set up with the exact same settings and I literally held them side by side and all setting are identical

What do you think the problem could be?