"at" command not working correctly

I'm trying to schedule some backups by using the AT command in dos but when i type in the line to schedule it and hit enter, it comes back saying "access denied". I've done this exact same line on another nt machine and it works great.
i've got the task schedule service running on the NT machine so it can't be that causing the problem.....
i've tried numerous at commands and they just won't accept them. i get the help info when typing "at /?".....it just won't save my schedules....
does anyone know what could cause "access denied" to be prompted???
thanks!

You'd probably have much better luck finding an answer to this one in the Windows NT forum.