live-migration fails with no errors in log files

The title says it all. I am stumped.

Here is an example. I start with describe instances
xxx@cloud-1:~/creds$ euca-describe-instances
RESERVATION r-hxh5bugl grmp_project default
INSTANCE i-0000000e ami-00000001 10.0.0.135 10.0.0.135 running None (grmp_project, cloud-3) 4 m1.small 2011-10-26T16:31:47Znova ami-00000000 ami-00000000
xxx@cloud-1:~/creds$ sudo nova-manage vm live_migration i-e cloud-2
Migration of i-e initiated.Check its progress using euca-describe-instances.
[.... after a while ....]
xxx@cloud-1:~/creds$ euca-describe-instances
RESERVATION r-hxh5bugl grmp_project default
INSTANCE i-0000000e ami-00000001 10.0.0.135 10.0.0.135 running None (grmp_project, cloud-3) 4 m1.small 2011-10-26T16:31:47Znova ami-00000000 ami-00000000

I have looked at the log files for compute on both source and destination machines. No error messages in there! The status of the machine changes to 'migrating' for a while before returning to running.

What could be wrong?