Help Group chat plz help!!!!!

[Lexi C]

Okay so I have a Samsung Note 2 and 2 of my friends have an Iphone 5c and the other I don't know. We have a group chat but the one with the 5c can't recieve messeges or she gets them a few hours or days late. The other girl can get them. When either of them try to start a new one, it fails to send. We deleted contact and conversations but nothing works. Please help!

Thanks in advance

Edit: Both have 5cs