Actual Expense cost in Activity usage profile didnt match Actual payment done in that month

Cost is added as Expense not resource. % complete type is physical. and duration is fix duration & units. Every activity has a fixed cost assigned under expense. Contract is design build. 
Contractor submit us monthly invoice generated from P6 which contains activities done in that particular month and their % complete/progress which after site visit and verification we approve. contractor submit schedule update 2-3 months late like June 2014 update submitted in Sep 2014 while payment is being done on monthly basis. 

While i was comparing the paid bills for months with schedule update (activity usage profile/ S curve) the actual expense cost in profile generated by same same schedule shows different values as actual expense cost..not the same we paid. 
e.g we paid 2 million in april, 3 million in may and 2.5 million in june. but now when i have received schedule update for june (data date 30 June) from contractor it shows higher actual values for these months (april may & june). I think it should match what we paid in that month as payment was made on progress. bt the profile is showing higher peaks as per scale if i compare it with actual payments. 

Please repl