grant privs resource manager

I was trying to user scott
resource manager privs using execute procedure.
It is not allowing...

SQL> conn / as sysdba
Connected.
SQL> conn scott/tiger
ERROR:
ORA-01017: invalid username/password; logon denied


Warning: You are no longer connected to ORACLE.
SQL> conn / as sysdba
Connected.
SQL> conn scott/scott
Connected.
SQL> conn / as sysdba
Connected.
SQL> exec dbms_resource_manager_privs.grant_system_privilege(-grantee_name=>'scott',admin_option=>true);
BEGIN dbms_resource_manager_privs.grant_system_privilege(-grantee_name=>'scott',admin_option=>true); END;

                                                         *
ERROR at line 1:
ORA-06550: line 1, column 58:
PLS-00707: unsupported construct or internal error [2603]
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored


SQL> execute dbms_resource_manager_privs.grant_system_privilege(-grantee_name=>'scott',admin_option=>true);
BEGIN dbms_resource_manager_privs.grant_system_privilege(-grantee_name=>'scott',admin_option=>true); END;

                                                         *
ERROR at line 1:
ORA-06550: line 1, column 58:
PLS-00707: unsupported construct or internal error [2603]
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored

What could be the reason..