The actually count of column got changed

[chalapathi]

I have a question about one of my report in cognos i have column name with Unique Billed...It shows that the "Unique Billed" was 25,048 for that day (9/17/09); however, when I ran the report on 9/17, the original number of Unique Premises Billed for that day was 144,328.  Why did the number change or could this be a defect?
                   Actually i am getting this proble for that day only, remaining all days it shows the correct data

           can you please provide me suggetions on this issue
             

[blom0344]

The first thing to do is to check the source of the data. So,relate the cognos object that performs the count to the actual object in the database and perform the check there (or ask your friendly DBA very kindly)
A very remote possible reason is that someone decided to update null values to another default. Typically count does not take into account nulls when performing its duty..