Share location works on one child's phone, but not the other.

I have a 5S. One son has a 5C, and his phone constantly shares location with me, which I set up by opening a text from me on his phone, going to DETAILS, selected Always share location. My other son has a iPhone6, and we did the same thing. Opening a text from me on his phone, we go to DETAILS and click Always share location. Except it's not working. To locate my son with the 5S (12y/o) I always open a text from him, click details and find his location. I still can't do that with the son with the iP6 (13y/o). As far as I can see all the settings are the same. I'm the one that set both phones up and I only know the Restrictions passcode. Is there another step to do this with a iP6?