using samba-quest in a cluster (using a virtual IP)

We would like to run Samba in a clustered environment and bind Samba to a virtual IP rather than the IP of the local host. This then means the VIP can move from one host to another for fault tolerance, etc. However, the VAS authenication breaks, I assume because samba is bound to and using the VIP for outbound connects, rather than the host IP address. The error we are seeing in syslog is:

Jul  9 13:00:38 duk1srv0134 smbd[20533]: [2007/07/09 13:00:38, 0] source/rpc_client/cli_pipe.c:get_schannel_session_key(2449)
Jul  9 13:00:38 duk1srv0134 smbd[20533]:   get_schannel_session_key: could not fetch trust account password for domain 'DHDOM1'
Jul  9 13:00:38 duk1srv0134 smbd[20533]: [2007/07/09 13:00:38, 0] source/rpc_client/cli_pipe.c:cli_rpc_pipe_open_schannel(2679)
Jul  9 13:00:38 duk1srv0134 smbd[20533]:   cli_rpc_pipe_open_schannel: failed to get schannel session key from server DUK2SRV0111.DUNNHUMBY.CO.UK for domain DHDOM1.
Jul  9 13:00:38 duk1srv0134 smbd[20533]: [2007/07/09 13:00:38, 0] source/auth/auth_domain.c:connect_to_domain_password_server(119)
Jul  9 13:00:38 duk1srv0134 smbd[20533]:   connect_to_domain_password_server: unable to open the domain client session to machine DUK2SRV0111.DUNNHUMBY.CO.UK. Error was : NT_STATUS_CANT_ACCESS_DOMAIN_INFO.
Jul  9 13:00:38 duk1srv0134 smbd[20533]: [2007/07/09 13:00:38, 0] source/rpc_client/cli_pipe.c:get_schannel_session_key(2449)

I set the following in the smb.conf to force binding to an IP:

   bind interfaces only = yes
   interfaces = eth0 10.87.220.15/16

Maybe I need to raise a support request for this; I will spend some more time on looking for a solution to this before doing so, though.