can't connect on socket

Backup started Sat Dec 27 12:49:44 2014

12:50:29 Initiating backup
12:55:34 INF - Server status = 25
12:57:22 INF - Backup by oracle on client bumisty3 using policy bucyclone_ORACLE
_sdblive, sched Weekly_Full_Offline:cannot connect on socket
misty3 #

any ideas appreciated

Paul