The Total Hours object in the Staff Productivity Collector is dependent on the presence of the Billable Hours (fdBillableHours) and Non-Billable Hours (fdNonBillableHours) objects on the Report Style. These two objects must be on the Report Style in order for the Total Hours object to work.  Drag and drop these two objects on the Report Style. If you do not want them to actually display on the Report Style, drop them somewhere on the side, right click on each and choose the Visible option.  This will remove the checkmark from the Visible option and will make the data objects invisible.