NPS access and failed logs not generating

Hi,

We have windows server 2008r2 with DC and we have integrated WLC with DC with the help of RADIUS server. Two days before we have enabled Audit Policy for Account, Directory and object changes with success and failure. After these changes NPS access and failed logs not generated on RADIUS server, before 2 days logs generated. Now only 4400 event ID generated on server. Users are accessing Wireless network. So please help me.

Thanks, Manish