Delphi Berlin Firedac - Error when string has & and @ characters

[JoeC]

I have a stored procedure that updates a string in a table.
It works from the management studio and it also works from a form in Delphi.
The only problem in Delphi is when one of the strings have the @ or & characters.
This is only a problem in Firedac, not in SQL.
I get this error message:
[Firedac][Phys][ODBC][Microsoft][SQL Native Client 11.0][SQL Server]String or binary data would be truncated.

[Norrit]

"String or binary data would be truncated" is normally when you try to save a string that is too long.
For example, you try to store a string of length 50 in a db field with length 40
I doubt this has anything to do with the @ and & characters

[JoeC]

The fields are both 30 char. The controls are limited to 30 characters.
The program works fine and only raises the error when there are @ or & characters on one of the fields.