关于创建UTL_TCP/HTTP/SMTP 的访问控制列表，提示网络权限无效,该如何解决

关于创建UTL_TCP/HTTP/SMTP 的访问控制列表，提示网络权限无效
begin
dbms_network_acl_admin.create_acl (
acl => 'TCP_CONN.xml',
description => 'Normal TCP Access',
principal => 'connect',
is_grant => TRUE,
privilege => 'username',
start_date => null,
end_date => null
  );
end;

执行上述语句，提示如下：
错误报告:
ORA-24245: 网络权限无效
ORA-06512: 在 "SYS.DBMS_NETWORK_ACL_ADMIN", line 252
ORA-06512: 在 line 2

[解决办法]
Oracle Error :: ORA-24245
invalid network privilege

Cause
The network privilege being added to the access control list (ACL) was invalid.

Action
Ensure the network privilege that you are adding to the access control list (ACL) is valid.
[解决办法]
这两个参数的赋值反了
principal => 'connect',
privilege => 'username',


参考http://www.oracle-base.com/articles/11g/fine-grained-access-to-network-services-11gr1.php