SQL & PL/SQL

Hi,
in 10g R2 , I created (code found in David Kurtz article) a function as follows but when use it I receive an error :

SQL> CREATE OR REPLACE FUNCTION h2i (p_hash_value NUMBER) RETURN VARCHAR2 IS
  2  l_output VARCHAR2(10) := '';
  3  BEGIN
  4  FOR i IN (
  5  SELECT substr('0123456789abcdfghjkmnpqrstuvwxyz',1+floor(mod(p_hash_value/(POWER(32,LEVEL-1)),32)),1) sqlidchar
  6  FROM dual CONNECT BY LEVEL <= LN(p_hash_value)/LN(32) ORDER BY LEVEL DESC
  7  ) LOOP
  8  l_output := l_output || i.sqlidchar;
  9  END LOOP;
 10  RETURN l_output;
 11  END;
 12  /

Function created.

SQL> select SQL_PLAN_HASH_VALUE, sql_id ,h2i(SQL_PLAN_HASH_VALUE) from v$active_session_history;
select SQL_PLAN_HASH_VALUE, sql_id ,h2i(SQL_PLAN_HASH_VALUE) from v$active_session_history
                                    *
ERROR at line 1:
ORA-01428: argument '0' is out of range
ORA-06512: at "SYS.H2I", line 4

ANy idea ? Any help ,
Thank you.