Further report anomalies

I have scheduled reports that run at 6am on the first of every month, and I doiuble check these when I get in in the morning, which this month was the 2nd(I am the first in office, and there is no possibility of others closing requests prior to my manual reports.
Here is the funny thing, between running the reports I get different figures
Completed requests by priority 0600am 01-06-08 = 1215
Completed requests by priority 0912am 02-06-08 = 1258
Requests by Group 0927am 02-06-08 = 1269

See attached for better example of reports etc

I am at a lose as to what shows exactly what has been closed for the month period?? Which figure is correct, and how do I justify my results when asked for reason for differences?

Hope someone can help me