Is this registration with social network credentials or when you hit the Register button on the SCLogin module? If it's the register button, SCLogin is simply redirecting the registration to the extension selected in the "Registration Component" setting and we wouldn't be throwing that error. I tried logging in via FB credentials on your site, and your application is still in development mode, so I an unable to test. Either way, please provide more details on the steps to reproduce your problem.
-Melissa