At the moment, I'm building some reports in SQL Reporting Services. A nice task, as always, and it does provide for some unexpected challenges once in a while.
Here's what happens in Reporting services when you use parameters – in fact, I had this particular issue quite a few times – I only just found how to get around it.
Problem description: When using a multivalue report parameter with all values selected by default, in fact, none is selected.
Solution: add the filter IS NOT NULL
I can't begin to explain how hard I hit my forehead with the palm of my hand when finding this one out J