Using the Git Plugin with Gitosis

Hi.  We are trying to get our Git repositories working with TC.  We use Gitosis for authentication but at the moment it's causing us issues with the TC Git plugin.  Any help would be most welcome.

So, I've added the build user to the gitosis configuration - added the user to gitosis.conf and the key to the keydir folder.

In the New VCS Root form, we need to specify the clone URL which is gitosis@pegit1:framework.git where gitosis is obviously the gitosis user.  Then we need to setup the Authentication Method, which I have specified as Private Key.  Then I point to the build user's key but when I click Test Connection, I get the following error:

Unable to load identity file: c:\GitID\build

Where build is the private key file.

Am I doing anything obviously wrong?  Has anyone gotten TC working with gitosis?

Thanks.