Wrong total in table object

I would also check your data.  I work for a similar company and where we run into problems with reporting like this when an associate bills time for a different office than his own.  For example.  We will have Associates in Office A, work on a project for Office B.  The Billable hours are recorded as going to Office B, even though the Associate works in Office A.  What happens then is our managers in Office A filter for Office A, and see "wrong" results.  However, if they select all the individuals from Office A, the numbers are correct.  This happens becuase the hours are associated by Person, and project, and not really by the office of the staff completing the hours.  

I hope this explanation helped.