PMM Error, any advice?

[sam.o.neill]

I get followng error, trying to use the PMM:

Error: Unable to create migration session: Unable to run 'supervisor '/opt/psa/PMM/var/2008-04-29-13.55.15.134963'': Unable to start supervisor: exceptions.KeyError 'getgrnam(): name not found: psaadm'

Any idea on that?