Unable to run this job due to a cluster error, please retry it later

And I've got this message in my nohup:

galaxy.jobs.runners.pbs DEBUG 2012-06-08 10:12:12,030 (453) pbs_submit failed, PBS error 15023: Bad user - no password entry

I use a galaxy user to launch my Galaxy server.

I already done all steps described in "Unified Method" like this command:

sudo usermod -s /bin/bash galaxy

Please, I need help !!

Thanks a lot,

Marc BRAS

Fondation Imagine

156, rue Vaugirard

75015 PARIS