login & password aging

Hi! I have a problem concerning password aging on SuSE 6.3. If a password expires the user is prompted for the new password at the login time. The problem is that he/she can enter an empty one just by hitting Enter twice. No checks for minimum password lenght, no cracklib checks - and these are enabled in etc/login.defs. Changing the password from the prompt works normally with all the checks in effect. So, is there a way to enable atleast the minimum password lenght check? Any comments and/or suggestions would be appreciated. Regards, Daniel.