[Plugin: PhotoContest Plugin] Photo Contest: Captcha Problem

Hi,

i have a problem with the Captcha.
Captcha is set to “True” so that it is not shown.
But when I vote on a picture it says that I enter the wrong captcha o.O but there is no captcha.

Can someone please tell me whats going wrong.

Greets

https://www.ads-software.com/extend/plugins/wp-photocontest/