Help Contact not receiving SMS

[Android Question]

Hi, I'm hoping you can help me. I have a Samsung Galaxy S4 and have recently started using GO SMS Pro as my default messaging app. A couple of times recently I've found out that my sms's have not been recieved by the recipient. From my end the messages appear to be sent, but then I find out later that the other person did not receive anything. I'm concerned that this has happened a number of times, and I'm not sure what to do.

 

[Hadron]

Most people in this forum would tell you to choose a different SMS app, though that's because the Go apps have a tendency to spam you with adverts for paid Go material (themes etc). But if the problem only started when you switched to that app then using a different app is the obvious solution.