Hi,
I just did a couple of tests on your site and I saw the following message when examining your page via firebug:
<b>Warning</b>: curl_setopt() [function.curl-setopt]: CURLOPT_FOLLOWLOCATION cannot be activated when safe_mode is enabled or an open_basedir is set in <b>/nfs/c02/h08/mnt/17101/domains/fusionconcepts.com.hk/html/wp-content/plugins/contact-form-7-autoresponder-addon-plugin/inc/Mailchimp.php</b> on line <b>256</b>
I recommend that you talk your host provider and show them that message and ask them if they can turn safe_mode off or do something about the open_basedir config on your server.