Contact Form 7 & Really Simple Captcha

I encountered a problem with Really Simple Captcha & Contact Form 7.

I can see the image, I can type the image data into the Captcha field…however, the message will not send. It returns an authentication issue wend sending the message.

Could this conflict be created due to using another Captcha plugin elsewhere on the blog?

The only place I am using RSC is within Contact Form 7 due to RSC being less secure.