Question : Can't get checkbox to check if query criteria exists

I have a form which contains a checkbox which by default is false.  The name of the check box is "chkbxSerial".  I need this checkbox to appear checked, or true after an afterupdate event has taken place on a combo cox.  The combobox has a query as its rowsource.  The query has a table as its recordsource.  In the query the field "Serial" is the 4th column.  So in the after update event of the combobox I have this VBA code...
'Me.chkbxSerial = Me.cboPartN.Column(3)
Why won't the checkbox be checked if the query field is true?

Answer : Can't get checkbox to check if query criteria exists

select concat(year(YourDate), '-',Month(YourDate)) from table