This formula is not working. Can you please help me correct it?

=IF(AND('Employee Attendance'!3:3DATEVALUE("4/1/08"),'Employee
Attendance'!3:3<DATEVALUE("4/31/08")),"","Yes")

If any cell in the line has a date of 4/1/08-4/31/08 entered, then I need it
to return as blank. If false (no date in that range), then I want it to
return "Yes".


Thank you.