If function problems
The error message says
The specified field can't be found
That can result from"
1. Incorrect syntax
2. Typo in a field name
3. Forgetting to include text values in quotes
And you should get a clue as to what is wrong by what part of the text is Highlighted when this error appears.
You are welcome to copy and paste your expression into Post a New Answer if you cannot figure this out on your own.
Retrieving data ...