Are you sure that there are any records that meets the filter criteria? To test, try SET FILTER TO .T. IN MONTH.

And, by the way, always issue a LOCATE after the SET FILTER line. So the sequence will be

select month
set filter to not completed
locate

But, as Nadya also pointed out, an updatable view is a better solution.

>So when I use the set filter to command, why does my month table appear empty, yet those are records in this table.