Fbgraph

Hi All,
Am new to rails ,am using fbgraph gem in rails 3 having the follwoing error

   {
"error": {
"type": "OAuthException",
"message": "Invalid redirect_uri: Given URL is not allowed by the Application configuration."
}
}

In my controller,

def start
redirect_to client.authorization.authorize_url(:redirect_uri => “http://localhost:3000/” , :scope => ‘email,user_photos,friends_photos,publish_stream’)

end

i want to post,poke to friends via my app ,is any other plugin available for this .

Thanks in advance