NTP client cannot sync date from a specific Server

I want to create a NTP server, and my clients could sync date from this Server. So I add restrict policy in my server, and then restart the NTP service to my it works as a NTP server. Then I add this server to my clients, and remote other NTP servers and pools to make it the only NTP server in this client. I have already run this command to check this server chosen by the client:

ntpq -pn

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*xx.xx.xx.xx     91.189.91.157    3 u  342   64  340    0.087    8.349 4492269

As you can see, it works fine. I also run **ntpdate -q xx.xx.xx.xx** to check the time by hand. But I want to change a specific time in my NTP server, so I disabled all the pools in my NTP Server, and then using **date -s** to change the time. I also restarted this Server. The problem is that when I finished all these steps, the client cannot sync the datetime from my NTP server!

ntpdate -q xx.xx.xx.xx
server xx.xx.xx.xx, stratum 16, offset -26584.931234, delay 0.02574
27 Aug 07:23:49 ntpdate: no server suitable for synchronization found

Does that mean I still need to define a pool or a server in my NTP server, and how could I change a specific time in my NTP server?