auditd start failure

HI Suddently, my auditd can't start. I do not know why. I remember I changed some permission settings on /var/log/audit. However, even I change it back, the auditd cann't be started. I looked at the audit.log. It only shows the daemon is closed successfully I wonder whether there is other log file I should look. Normally, it will print out the failure reason : wrong audit rules but this time, only "Failed". thanks a lot