Access requests logging to SQL: How to save comments for rejected requests?

Hi. I am using FreeRADIUS 2.1.12. I tried to save results of process access requests to SQL database using postauth_query. I used 'Module-Failure-Message' attribute as a comment for rejected requests. The message 'rlm_pap: CLEAR TEXT password check failed' drops to database when password is wrong, for example. But attribute 'Module-Failure-Message' ( and attribute 'Module-Success-Message') is empty when user not found, for example. And other reasons may be. How can I save comments for rejected requests?