Sales Analysis Reports Show Different Totals For Same Sales Rep in 7.20.2.000

Good Morning,

When i run Inventory Sales Analysis report and on the Sales Rep option i select a single Rep i get a different total for that One rep than when i run the same report and i select all Reps on the Sales Reps option.

What could be the issue, the build is 7.20.2.000

Regards

Blessed