[otrs] Varying reports for solution time escalations. what could be the reason

Hi All, I am facing issues in stats for solution time escalation reports. The statistics for solution time escalations in a specific period is varying when we execute report on different dates. For eg. On a Queue <XYZ> there were 10 solution time escalations for the month of September when the report was executed on October 5th. Again when we ran the same report on October 10th the escalations are 5. What could be the reason? Please help. Thanks and Regards, Lokesh