likely the issue is that you are evaluating Nulls.
If your formula option or report options are not set to handle nulls then the formula will stop evaluating when it hits the null (which acts the same as a false in the select expert).
if you are using Ryan's suggestion and you have a formual field with to return a T/F on the 3 date ranges change that formula field to use the option of 'use default values for nulls' and palce it on your report canvas to see if you get TRUE and FLASE on each row as you wanted it to.
your statement would be similar to Ryans suggestion.
Edited by DBlank - 22 Feb 2012 at 3:38am