plugins not responding

I am having a problem with a plugin for my wordpress installation. It is a script(wp-keitaimail.php) designed to allow me to post to my wordpress (www.keyoperating.com/cms) by way of an email address ([email protected])

I tried the original builtin wordpress plugin to post by email but it never worked.

It requires an email forward to the script that Startlogic has setup already. But when I send an email to [email protected] it comes back and is returned with the following error.

error:
/Warning: main(/home/keyopera/public_html/cms/wp-includes/class-xmlrpc.php): failed to open stream: No such file or directory in /home/keyopera/public_html/cms/wp-content/plugins/wp-keitai-mail/wp-keitaimail.php on line 31
/Fatal error: main(): Failed opening required ‘/home/keyopera/public_html/cms/wp-includes/class-xmlrpc.php’ (include_path=’/home/keyopera/public_html/cms/wp-content/plugins/wp-keitai-mail/:.:/usr/local/lib/php’) in /home/keyopera/public_html/cms/wp-content/plugins/wp-keitai-mail/wp-keitaimail.php on line 31
I’m not going to try again; this message has been in the queue too long.