Top-of-Page - Count of documents missing when range of date not provided el

Hi Gurus!

I have given an option in my report o show the total number of distinct sales documents in my report in my top-of-page. It works well and fine and shows me the total number of sales doc when athe report is run based on a particular selection criteria, also I have a column to show the number of line items in the report.

The problem arises and which si , when I run the report and in the selection screen when I give a date range i.e 01/07/2008 to 01/31/2008 in between such and such date it gives the total number sales document output in the top-of-page in the top but when I give just one date i. e 01/07/2008 , it gives the output without the top of the page having the number of sales documents. Can I get some help as to why its not showing when only one date is given and shows up when a range of date is given.

Regards

Aarav