Problem with BR and RR routers

Yesterday morning, when i tried to ping from RR to BR but it cannot work. So i tried to troubleshoot and when i do a show ip route, the network addresss for the connection between RR and BR serial interface is not shown.

By right, for both BR and RR there must be a 200.10.10.64 network when show ip route. However, this thing is AUTOMATICALLY solved when i came back from lunch.