This may have two reasons, which all take place in two advanced ways of citadel installations. * You've installed WebCIT behind an apache with mod_proxy. In this case you need to make sure WebCIT is started with the -f commandline param, so it accepts apaches X-foo headers.
- You've installed WebCIT on a different host than Citadel (for example to gain performance). In this case you need to add the IP you see in the public_clients file in your citadel configuration directory. After altering, citadel will reread that file.