Why isn't my group texting option working?

[AC Question]

I have recently switched from Family Mobile service to Straight Talk AT&T service for my Samsung S3. Group texting was working fine with Family Mobile. Now with Straight talk, it takes HOURS to send a group message (with only 2 people) or it doesnt send at all. Please help! Group messaging is turned on.

 

[dpham00]

Do normal texts work ok?