An unexpected error, right?
SQL> CREATE PROFILE TEST_PROF LIMIT FAILED_LOGIN_ATTEMPTS 5 PASSWORD_LIFE_TIME 180 PASSWORD_GRACE_TIME 30 PASSWORD_REUSE_MAX 15 PASSWORD_VERIFY_FUNCTION fnc_validation; CREATE PROFILE TEST_PROF LIMIT * ERROR at line 1: ORA-28004: invalid argument for function specified in PASSWORD_VERIFY_FUNCTION FNC_VALIDATION
That is a simple need. You have to use 3 parameters on function: username varchar2, password varchar2, old_password varchar2.
Matheus.