Disqus problem with wordpress “unable to connect to the disqus api servers”

I recently installed Disqus plugin for WordPress; however, I have been receiving this message “unable to connect to the disqus api servers.” By looking into the source code, it looks like curl is the problem! more specifically the _dsq_curl_urlopen() function, but I did not investigate this error further. As fortunately, we can easily switch to the alternative function _dsq_fsockopen_urlopen().