[问题]User does not have permission to use the "at" command

[heropaladin]

sybyl的一个程序不能运行，检查日志发现如下报告：
User xs does not have permission to use the "at" command on this machine。 The batch job will be submitted to run as a background process.
Contact your system manager to enable your account to use "at".
我已经是管理员用户了
如何修改
期待解答

[BigSnake.NET]

xs 没有权限

[heropaladin]

即使我到root权限下也会出现这种情况，日志就变成user root does have the permission
怎么回事？