Text message rule error

I’m trying to send a text message to a certain group of patients. I keep getting the error message :
[syntax error at or near “)”]

I haven’t placed an end bracket in the message, nor are there any filters that are being used with text characters that aren’t normal a-z 0-9 type characters. Even when I removed things like % signs, and @ signs, I still get the syntax message error.

I can send other text messages (appointment based reminders) but I can’t seem to send a text message as a single one off bulk text message to the people who have agreed to have text messages sent to them. Can you help?