red hat U$ bind 问题

安装好U4的所有程序后，启动bind(service named restart),查询bind状态（service named status）后，出如下错误

rndc: connection to remote host closed
This may indicate that the remote server is using an older version of
the command protocol, this host is not authorized to connect,
or the key is invalid.

请问哪里出错，怎么解决？key文件已配置好。