I was able to solve the problem of the blank screen dues to the fact that i was using another plugin with the same api. Now that i'm starting to use this plugin i've a problem with the settings. After clicking on the "sign in" button a popup appears to agree to the connection. Once the button is clicked the site goes to the home page and the connection is not realized. So: nothing happens!!! Are you so gentle to explain me how i've to set the application and the plugin for connecting correctly!?!?