error on qsub/mpirun jobs

I have a a mpiblast job that runs well on command line ("mpirun").
But have errors when "qsub" to run:

qsub -l nodes=6:ppn=2
     -e /path/to/locationA
     -o /path/to/locationA
     /path/to/program

----------------------------------------------------------
Unable to copy file /var/spool/torque/spool/658.nagrp2..ER to
hu@hist:/raid/pub/ncbi/blast/www/mpiblast.tmp
>>> error from copy
Host key verification failed.
lost connection
>>> end error output
Output retained on that host in: /var/spool/torque/undelivered/658.nagrp2..ER
----------------------------------------------------------

Note: When manually check, the "retained" file is not there: 
"/var/spool/torque/undelivered/658.nagrp2..ER"

I wonder why "Host key verification failed"?  Could this be the cause?
(I can ssh to all nodes no problem)

Any hint to look further is appreciated.

Zhiliang