The storage time and end time of the session difference several hours in session results.
1 Adjust the time zone of firewall to keep it identical with the time zone on log server, for example:
clock timezone c8 add 08:00:00
2 Adjust the time of firewall to keep it identical with the time on log server. For example:
clock datetime 0:0:0 2011/11/01
The time and time zone is different between log server and firewall.