ORA-24347: Warning of a NULL column in an aggregate function

select statement:
select grantee from dba_role_privs where granted_role = 'G0645_ADMIN';

error
ORA-24347: Warning of a NULL column in an aggregate function


I don't know what i'm doing wrong!! please help

Problem Description
-------------------

Running an aggregate function and get error:
ORA-24347: Warning of a NULL column in an aggregate function.

Solution Description
--------------------

You are running into Bug # 1149002, which states it will be fixed in version 8.1.7.

A backport request BUG: 1459188 has been filed already for version 8.1.6.


Check metalink for details

Sam

Thanks!