Why can't I invite friends to my squad?

[Powwowpow]

When I invite my friend to my squad, he never came. He didn't reject it. Is this a bug. Any help will be appreciated.

 

[Random Person]

Are you sure if you're with him? Do you both have same platform? Like iOS or Android. Did he ever accept it or he's just faking it some ways to not join your squad?
1. You better check it out what's happening to his game.
2. REMEMBER: There IS absolutely NO cross-over from different types of platform!
3. Maybe he might be telling the truth or what?

 

[Powwowpow]

Oh yea. He doesn't have the same thing as me. I am so dumb. Thanks man.