Unable to login using Ultimate Facebook on other pages than home page

Hi all,

I've two problems with Ultimate Facebook Plugin which are causing me from fully using it.

The first one is that I can't login with facebook using php to call shortcode ( <?php echo do_shortcode(); ?> )in another login widget (Sexy Login) since I love this login widget look. Whenever I tried to login, it will redirect back to the page I was currently at with the login form again. I would have to do the refreshing on the page one more time or visit another page in order to see the my login menu. I'm not sure if this is because of the W3 Total Cache I'm using. But just to let you know that if I login with Sexy Login form direct, this problem doesn't happen at all.

Second one is that other people can't seem to use the facebook login function on other page at all. When they click login with facebook, there will be a popup from facebook saying that an error has occur and ask me to try again later. This problem is not happen at all if I login with my facebook account, however; it will always happen with other facebook accounts.

Please kindly help me out on these.

Thanks.