Failed login attempts

Hi,

I have a Non-Trusted HP-UX System, I wanted to lock users after three
failed login attempts .

I have made a entry in /etc/default/security as follows

MIN_PASSWORD_LENGTH=8
PASSWORD_HISTORY_DEPTH=10
AUTH_MAXTRIES=3

but when i tried to test this the account dosent get locked out,Can
someone tell me hwo to fix it.