[CentOS-virt] Xen live migration

I can't get xen live migration to work - CentOS 5.6. I have set up xend-config.sxp as per RHEL5 virtualization guide, but when I try it, I get

[root@xenhost1 ]# xm migrate testwww xenhost2 -l Error: (104, 'Connection reset by peer') Usage: xm migrate <Domain> <Host>

Migrate a domain to another machine.

Options:

-h, --help Print this help. -l, --live Use live migration. -p=portnum, --port=portnum Use specified port for migration. -r=MBIT, --resource=MBIT Set level of resource usage for migration.

Any ideas what to check? brctl, xend-config.sxp, lsof, are all in agreement with http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualiza....