Blank page after posting comments

Dear Support,
I chose you dzonia-lite them for my wedding website.
However i’m not able to use the blog section, since after posting a comment, I receive a blank page and the comment is not posted.
I also checked the content of the returned page and it is really blank (I mean empty body).

Could you please provide some hint to understand the issue?

I read a plethora of posts complaining about this issue in many themes. Most of the time there is some code to be added. But in case of your theme I do not know where exactly.

Thanks in advance