Can't install Exchange Gateway

[msdcit]

I'm trying to install the Exchange gateway on an Echange 2003 system. Have installed C1 with snapins and created a secondary GW domain for the gateway on the Exchange server. The secondary domain starts up OK.

However, when I try and install the gateway on the Exchange server, it fails wi the error 'Unable to get Exchange Server Sites for the server servername and the organization orgname'. If I OK that message, it takes me to the dialog to select the server site, etc, but there is nothing to select, so I have to cancel out of the install.

Any ideas?

Rob.