[tor-relays] Advice on configuring Obfsproxy3 transport?

Attempting to get Obfsproxy3 to work.

With Tor v0.2.4.11-alpha and Obfsproxy pulled from https://git.torproject.org/obfsproxy.git yesterday this is what I get at runtime:

Apr 05 14:57:23.000 [warn] Server managed proxy encountered a method error. (obfs3 could not setup protocol) Apr 05 14:57:23.000 [warn] Managed proxy at '/usr/bin/obfsproxy' failed the configuration protocol and will be destroyed

I have no problems with obfs2, but obfs3 success continues to elude me.

These are the relevant lines from my bridge config:

ServerTransportListenAddr obfs3 aaa.bb.cc.dd:12647 ServerTransportPlugin obfs3 exec /usr/bin/obfsproxy --managed

Any advice on how to get Obfsproxy to work would be greatly appreciated.

Thanks.