I am using a countif function in MS Excel. It is counting the instances that
a particular date/ time occurs in a list. The function references the
criteria in an adjacent cell as follows

In cell A2:
9/1/06 5:00 PM

In cell B2:
=countif( D2:D30,A2)

The countif function won't calculate until I double click on cell A2 which
puts a cursor in it and then hit enter on my keyboard. Any ideas on why I
have to click the referenced cell to get the formula to calculate?