reCatcha problem using reCaptcha plugin and theme from GeoDirectory

Hi there
It appears I'm getting the following message but I don't know from where.
“POST http://mydomain.com/subsite/wp-comments-post.php 500 (Internal Server Error)”.

I've been trying to test leaving a review but getting the following message even though I'm not asked to complete a reCaptcha.
"The reCAPTCHA wasn't entered correctly. Please use your browsers back button and try again."