ExcelBanter - Delete some substotal in a pivot table

Hi,

I have a pivot table that show all the working hours for a group of
employes. I've created a calculation for the overtime (total hours of work -
40 hours) and added that column in my pivot table. This way I can see hoe
many hours of overtime each employes have done. The problem is at the
substotal level for each boss; the system take the total hours for the "Boss"
minus 40 hours.

Ex:
NOW
Mister A 45 hours of works; 5 hours of overtime
Mister B 40 hours of works; 0 hours of overtime
Total for all emp of Boss Y 85 hrs of works; 45 hrs of overtime (85-40)

Should be
Mister A 45 hours of works; 5 hours of overtime
Mister B 40 hours of works; 0 hours of overtime
Total for all emp of Boss Y 85 hrs of works; 5 hours of overtime

Can I hide the substotal for the column overtime or can I change something
else to obtain the correct number of hrs?

Thanks in advance