Hornetq failover doesn't work

I tried to set up backup server for JMS subsystem. I act upon this tutorial (shared store) https://access.redhat.com/documentation/en-US/JBoss_Enterprise_Application_Platform/6.4/html/Administration_and_Configuration_Guide/sect-High_Availability.html#Configuring_HornetQ_Shared_Stores

When I killed the LIVE server, BACKUP server took the control as I expected. However the problem occurred when I started the LIVE server again. LIVE server stopped the BACKUP and then the BACKUP threw an exception. After that warnings started to occur in the log of BACKUP. When I killed the LIVE again, BACKUP didn't take the control again. See attachments.