Would you be attempting to install the Server Tools kit directly onto an OS X Server 10.6.8 system? If so, please don't do that. The integrated versions of the Server Tools — despite the version numbers displayed by the tools — are the correct versions for the underlying version of OS X Server. Software Update for OS X Server does correctly manage and upgrade the integrated Server Tools kit.
If you're testing with multiple versions of Server Tools installed on OS X client and accessing a remote OS X Server 10.6.8 system, then are there any relevant errors logged in the local console logs on the client or in the servermgrd daemon logs on the server? In general, the Console.app tool is usually better at viewing the logs than the integrated viewer within Server Admin.app, too.