The first iMessage to another user won't send from my Macbook Air

[Paulsgirl1]

Its only the first message that gets stuck for some reason and shows an exclamation mark. Its to any of my friends that are on iMessage. Any ideas on what the issue may be?

 

[Alli]

If they send you one, can you reply?

 

[Paulsgirl1]

Hi Alli,

Yes I can reply. But they don't get the first message so I have to send a second which will go through. The first will just show an exclamation mark beside it.