Using SUMPRODUCT to count

Let's look at the example below,

In column C dates and column D the error happened on the day with possible multiple entries.

The requirement is to calculate the number of times error5 occurred after 5/5/2012 and before 5/15/2012. (answer is 5).

Lets put the two dates in A1 and A2. The formula will be 

=SUMPRODUCT((C1:C22>A1)*(C1:C22<A2)*(D1:D22="error5"))

If you do not want enter dates in cells the formula will be 

=SUMPRODUCT(($C$1:$C$22>DATE(2012,5,5))*($C$1:$C$22<DATE(2012,5,15))*($D$1:$D$22="error5"))

Love to have your comments....