Why does it take a long time to download group conversation messages?

[AC Question]

Even i f my phone(Samsung Galaxy Grand Prime) has mobile data on, it takes up to an hour for me to be able to read them. I push "Download" a number times, but nothing. I've sent a picture to myself, and the same thing happens...it's stuck in "Sending", and I could see it only when I get the other messages.

 

[B. Diddy]

Welcome to Android Central! Who's your carrier? Make sure your APN settings are correct.