Hey @Carrie1956! Philippe here. I hope you're doing well. 
Can you send us a screenshot of the error in question please (while concealing any personal information)?
Also, are you sure you're you're not trying to send an MMS (picture message) and not an SMS (text message)?
You need your data turned on to send MMS mesages.
Hi @Carrie1956 , I know how frustrating that can be. It happens randomly to me on occasion and always to my friends on Telus. No rhyme or reason to it. There's many different suggestions on how to fix it and different tricks work for different people. I downloaded the updated Google messages app and seem to have more success with that one. If one gets stubborn and doesn't send, I copy the text, delete the first one and then paste it and hit send again. So far it works for me. I also have had it work when I restart my phone and hit resend after my phone is finished turning back on. I hope one of these ideas works for you. It's hard to tell what causes it for some people.
I'm using a Samsung Galaxy 10e. If that's a common thread.
