no messages received after reconnected

Thanks a lot.
First, A set cleansession = false, connects to the mosquitto, and subscribe a topic T;
Sec, B connects too, and publish a message with T, A got it!
Third, A disconnect, B send some messages with T
Four, B disconnect, then reconnected, subscribe the same T, but no messages received.

And also B reconnect using the same client id.

I set mosquitto.conf default.