Undefined index: ebd_downloads

I just use to single download something like:
[email-download download_id=”166″ contact_form_id=”236″]

And contact form 7 (id=236) is very simple:
[text* your-name]
[email* your-email]
[text your-subject]
[textarea your-message]
[submit “Send”]
I always get this error on version 3.2.8:

<b>Notice</b>: Undefined index: ebd_downloads in <b>/home/xxx/wp-content/plugins/email-before-download/email-before-download.php</b> on line <b>424</b>
{“mailSent”:true,”into”:”#wpcf7-f200-p19-o1″,”captcha”:null,”message”:”Your message was sent successfully. Thanks.”,”onSentOk”:[“document.getElementById(‘wpm_download_1’).style.display = ‘inline’; document.getElementById(‘wpm_download_1’).innerHTML='<p>You can now download our brochure<span class=\”et-icon\”><span>brochure<\/span><\/span><\/a><br \/><\/strong>.<\/p>’; “]}

Can you give me an advice?

http://wordpress.org/plugins/email-before-download/