Got it -- Empty dates in the table were causing this. It's working fine now that I've filtered them out.

>I'm running into a problem with date functions not working when placed in a SQL statement:
>
>This works:
>
>? Date(Year(tbl.myDate), Month(tbl.myDate), 1)
>
>This returns "Function argument value, type or count is invalid":
>
>select Date(Year(tbl.myDate), Month(tbl.myDate), 1) as myDate from tbl
>
>What am I missing here?