Facebook OAuth 2.0 Login Icons not showing

So when I use Facebook's PHP SDK 3.0.1, using their example.php (you can find it all here ), I cannot get the nice icons (like you might see on the right side of groupon's signup site: https://www.groupon.com/users/new).

The weird thing is that when I use an older version, like 2.1.2, they appear just fine if I add the following two lines (the ones inside the double asterisk) to facebook.php:

public static $CUR开发者_如何学CL_OPTS = array(
  CURLOPT_CONNECTTIMEOUT => 10,
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_TIMEOUT        => 60,
  CURLOPT_USERAGENT      => 'facebook-php-2.0',
  **CURLOPT_SSL_VERIFYPEER => false,
  CURLOPT_SSL_VERIFYHOST => 2**
);

Any help on this? I would like to be using the most recent version of Facebook's PHP SDK, but I can only get a plain text "Login with Facebook" rather than the nice icon.

Try to make sure that the icon has both the correct path set and the correct permissions