How to use Jetpack? site_inaccessible IXR -32300

> Your website needs to be publicly accessible to use Jetpack: site_inaccessible Error Details: The Jetpack server was unable to communicate with your site [IXR -32300: transport error: http_request_failed Operation timed out after 15000 milliseconds with 0 bytes received]

I couldn’t connect to wordpress.com.
I tried following things.
– Tool -> Core Control -> External HTTP Access -> cURL Disabled
– wp-admin/php.ini extension=curl.so

http://blog.tmyymmt.net/en/
http://blog.tmyymmt.net/ja/
with Ubuntu 12.04 and lighttpd.

http://wordpress.org/extend/plugins/jetpack/