why when i click like button on my website, it always shows confirm button?

it's ok on my computer but when i posted it online, after clicked like it 开发者_运维问答always shows up a confirm button. here is my like button code:

 <iframe src="http://www.facebook.com/plugins/like.php?  app_id=231169313564386&href=http%3A%2F%2F{4}&layout=button_count&width=450&show_faces=false&action=like&colorscheme=light&font&height=21" scrolling="no" frameborder="0" style="border:none; overflow:hidden; width:90px; height:21px;" allowTransparency="true"></iframe>

here is picture:

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this is facebook's security to stop you "hacking" an account