If you get an error on the login page that usually means the credential are incorrect or the user does not exist in the database.
If no error then login was successful but if you don't appear to be logged in possibly your browser is blocking cookies so it fails to set an authentication cookie. Maybe check borwser settings or disable any kind of privacy guard software that you may have installed or try using a different web browser to see if you get the same result.
You say you installed it on a new server, was this a clean new installation or did you move an existing installaiton to a new server?
Are you using our precompiled deployment package or did you deploy your own builkd from source code?
I would also check the log for any errors.
Hope that helps,