Progress Reporting Reports

Hi i am fairly new to primavera im using Primavera P6 Project Management - release 7 - SP2.

When our Engineers enter their time in Progress Reporting i need to find actual hours for specific activities so i created some reports to feed back this information, i created them using the wizard. Trouble is Primavera isnt picking up on all the hours and when it does it doesnt calculate the totals correctly they are a couple of hours out. Not all the time but definately more often than not. I have checked and double checked the reports and there appears to be no errors on these, so i think it must be in the schedule i have built.