Access Error: #Error when trying to calculate or manipulate a field

=========
QUESTION
———
All I am doing is trying to do a calculation or manipulation on a field in my query, and it comes up with #Error rather than the results.

If I do the calculation in a test field, it works just fine – what’s going on?

=========
ANSWER
———
Obviously, this could be a thousand different things – but DOUBLE-CHECK your query fields.

Is it possible you are using a field name from some other place in your criteria where you are already doing a calculation, instead of what you think you are doing: getting it from the table itself?
This will cause that error every time!

Change all your field names in your calculation to absolute references: