Ensure that your Application is not in "Sandbox Mode". To do so, go to the
Facebook Developer Area
, click into your app and check the Sandbox Mode setting.
Beyond that, check or test that:
* Autotune has been run and automatically configured your Facebook Application properly
* Test on both www and non-www to see if there is a different behavior
* Try from different browsers and/or computers to see if it's specific to a certain combination
* Try from different Facebook user accounts
Let us know if any of the above narrows down a specific case where the problem occurs more. I just quickly went to your site and clicked the Login with Facebook button and was properly brought to the Login/Register page, so I'm not sure what is happening for you.
Thanks,
Alex