Email DLP Policy stopped working

Hi,

I have created one DLP policy for Email prevent, few days it works properly along with other polices, but suddenly e-mail violated by that policy is not getting blocked, however other pollicies are still working properly and I didn't make any changes. Can anybody help me to find the exact root cause and how to troubleshoot. In this regards I would like to inform you that I didn't find any error in my enforcer server and moreover If I copy this policy and save it with another name the policy is working fine.