Sougatab,
There's some piece of code on your site that either you've put there or is part of a plugin (not part of JFBConnect) that is redirecting the user to:
social-network-for-social-impact/profile
That code has a bug where it's redirecting without a / in front of the path I mentioned above. I don't know where this code is, but you need to fix it. There is no doubt this is the problem. When we disable the redirects in JFBConnect, the user should return to the page they were on when they clicked the Login with Facebook button. On your site, they are going *always* going to the social-network-for-social-impact/profile URL. If we turn on Automatic Registrations within JFBConnect, that process works normally. However, if we leave the "Normal Registration Flow" on where the user has to fill out information, the path is being appended to the JFBConnect registration URL, which is incorrect (likely because of a missing forward / on whatever is causing the redirect).
Again though, with our redirects disabled, the user shouldn't go to the profile page at all. You need to help me understand what is causing that redirect. JFBConnect's redirects work on thousands of sites, so there's something unique about yours that is skipping our setting and we need know what that is.
Hope that helps clarify. I've tried disabling the obvious plugins, but this could be a change that someone made to Joomla itself, or some other thing that can't be manipulated from the admin area.
Thanks,
Alex