WAF can not write logfiles, you see this problem in the Live log from WAF:
Live Log: HTTP reverse proxyFilter:Autoscroll
[FONT=monospace]2010:05:04-09:24:30 firewall reverseproxy: [Tue May 04 09:24:30 2010] [error] [client ***.***.***.***] ModSecurity: Audit log: Failed to create subdirectories: /var/log/audit/20100504/20100504-0924 (Permission denied) [hostname "***.******x.***"] [uri "/owa/ev.owa"] [unique_id "S9-LS...."] [/FONT]
[FONT=monospace]2010:05:04-09:24:30 firewall reverseproxy: [Tue May 04 09:24:30 2010] [error] [client ***.***.***.***] ModSecurity: Audit log: Failed to create subdirectories: /var/log/audit/20100504/20100504-0924 (Permission denied) [hostname "***.******x.***"] [uri "/owa/ev.owa"] [unique_id "S9-Lr...."] [/FONT]
[FONT=monospace]kind regards[/FONT]
[FONT=monospace]Alex[/FONT]