I just tried to authenticate using Yahoo and am getting an "Uh oh" error. It's hard to see, but if you look in the bottom right of that page, there's a message that says:
Developers: Please check the redirect URI in your request and submit again.
Please double check your Yahoo application settings. Specifically, make sure that the "Callback Domain" is correct or your site. In your case, it should be "africasted.com".
I hope that helps, but if not, please let us know and we'll gladly help investigate further.
Thanks,
Alex