Hi Marcus,
You need to enter the date (using the correct format; example May-29-2009). Once this is entered then you need to click on the little upside down triangle next to the date box and click on the specific criteria. For instance in this example, if you wanted all entries with date ‘May-29-2009’ then you would select 'Equal To' as the criteria. Taking this one step further, if you wanted to return all entries created in ‘May’ then you would enter ‘May’ and set the criteria as ‘Contain’.
As a tip, I noticed you are clicking the filter icon on the far right, if it’s more convenient you can hit 'enter' instead and that would also apply the filter :)