AD accounts not getting locked out properly ID 4771

Hello,

I'm receiving many event ID's for 4771 on several domain controllers where I'm getting the below information with many authentication failures but the user accounts are not getting locked out when the default domain policy is set to lockout after 3 unsuccessful attempts. Any thoughts? Thanks


4771,AUDIT FAILURE,Microsoft-Windows-Security-Auditing,Thu Dec 27 20:26:01 2012,No User,Kerberos pre-authentication failed.    Account Information:   Security ID:  S-1-5-21-2094812614-1962491401-1202159320-115256   Account Name:  bvn0412    Service Information:   Service Name:  krbtgt/domain.COM    Network Information:   Client Address:  ::ffff:10.12.104.105   Client Port:  62426    Additional Information:   Ticket Options:  0x40810010   Failure Code:  0x18   Pre-Authentication Type: 2    Certificate Information:   Certificate Issuer Name:     Certificate Serial Number:     Certificate Thumbprint:      Certificate information is only provided if a certificate was used for pre-authentication.    Pre-authentication types, ticket options and failure codes are defined in RFC 4120.    If the ticket was malformed or damaged during transit and could not be decrypted, then many fields in this event might not be present.