Can't get a standby built

Trying to rebuild my standby server (several times now). I know repeating something over and over while expecting a different result is the definition of insanity. But, I've always
started with:

/usr/pgsql-9.3/bin/pg_basebackup -h <masters_ip_address> -D /var/lib/pgsql/9.3/data -X s -c fast

I then copy my recovery.conf file into the data directory, check that everything looks correct, and try to start the standby. The log consistently says something like:

LOG: entering standby mode
LOG: restored log file "00000006.history" from archive
cp: cannot stat '/mnt/wallogs/archive/000000060000001200000059': No such file or directory
LOG: restored log file "000000060000001200000059" from archive
FATAL: requested timeline 6 is not a child of this server's history
DETAIL: Latest checkpoint is at 12/5B000060 on timeline 5, but in the history of the requested timeline, the server forked off from that timeline at 12/47000000.
LOG: startup process (PID 60870) exited with exit code 1
LOG: Aborting startup due to startup process failure

This routine has worked for me in the past and I don't understand why it won't work now. This is supposed to be a streaming replication standby server. So, do I have the wrong
flags for pg_basebackup? Or is something else going on?
--
Jay