eddycom on "[Plugin: Contact Form 7] Send button load continuously but does not show "Message sent successfully""

Hi,
After filling in the fields I click on Send. But the arrow runs continuously without the "message sent successfully". Well, email and sms (Clockwork plugin) are sent without problems. I don't know how fix it. I would be fine too, but for a user who expects a positive response is very unpleasant. Before working fine. Then I installed the Clockwork plugin and updated wp version 3.5.1, the message don't show. Any idea please? Thanks

http://wordpress.org/extend/plugins/contact-form-7/