what criteria will select a blank in a date/time field?

[challems]

I have a table with a field (date.time) showing sales dates. I am trying to
write a query that selects the records that have a blank in this field. The
operator Is Null creates a data type mismatch response. What criteria
expression will select the blanks in the Sales Date field? I am using XP
Office access program.

 

[Duane Hookom]

A criteria of
Is Null
will work with all data types. Are you sure your criteria doesn't have
quotes around it?