Bob not checked out your attachment yet but i was fiddling with this
which if the date fell between those in the formula it returned a value of 1 if it fell outside of the dates it returned a value of 0, i am assuming its because it is only checking for the occurrence of the date and counting the amount of times.....although i'm probably way of mark!=IF(AND($A2>="01 January 2007",$A2<="31 January 2007"),SUM(ROWS({"01 January 2007","31 January 2007"})),0)
Regards,
Simon