The name of the expression ("Expr1") is whatever the query picks up from the data - ie, if a contract is seen to fall due in 61-90 days, the column heading in the query (Expr1) becomes 61-90 and so on. This works fine in the query.
In the report I have designed based on this query, though, I have a problem. I cannot put a text control for the expression since there is none until I run the query. When I do run one, it is static (ie, a snapshot of data at that instant), and pulling in the appearing expression fields into the report does not update to a future running of the report when the query data would show other day periods when contracts fall due.
This results in a Microsoft error message that "The Microsoft Jet engine does not recognise '[- 0]' as a valid field name or expression". The field enclosed in the square brackets are any that the report does not find the data for in the query.