CAPTCHA problem: unexpected result from hook_captcha() of module draggable_captcha when trying to retrieve challenge type Draggable for form webform

Introduction:
CAPTCHA - Version: 7.x-1.3
Draggable CAPTCHA - Version: 7.x-1.2
Image CAPTCHA - Version: 7.x-1.3
Driupal Core - Version: 7.36

What I do
I Create a webform on node 240.
In admin/config/people/captcha I insert for form_id:webform_client_form_240 and "Draggable Captcha"

Problem
When an Anonimous user visit the form
1) Can't drag the right image (only can click on)
2) in th log file appear
CAPTCHA problem: unexpected result from hook_captcha() of module draggable_captcha when trying to retrieve challenge type Draggable Captcha for form webform_client_form_240.
3) after a period of some hours the captcha no longer appears and begins spam on the form

What can I do ?
Thanks