I am trying to write an Countif statement that I will eventually turn into an
array. However, I am having problems with the dates. My statement now is:

Countif(A1:A100,"<=B1")

In this statement A1:A100 are all dates, and so is B1. The function just
gives me zero. However if I change the statement to:

Countif(A1:A100,"<=1/1/2009")

Then the statement works. If I physically type in the date it works fine,
but when I try to have it look up the date from another cell it doesn't work.
Any ideas?

Ulimately I want the equation to be

{=Count(if((A1:A100,"<=B1")*(C1:C100,"=B1),(D1:D1 00))}

I need to get past the first error before I can proceed.