Why is the exclamation point still next to my contact name on go sms pro?

[AC Question]

I was trying to send a text n it kept saying retry wit retry option next to the text even after the text message was sent after going back to my text log on go sms pro the yellow triangle wit the exclamation point is still there! I even delete the app n install it back n it's still there! How do I get rid of that annoying icon next to my contact name in my text log on go sms pro without deleting anything??