Custom contact form - global $response not loading

Hi,

I've created a custom contact form from yours manual on blog: https://premium.wpmudev.org/blog/how-to-build-your-own-wordpress-contact-form-and-why/ because I needed to embed some values from custom-fields in it.

Everything looks fine, here, but it's not. I have problem with displaying the $response message - even empty (which is now set as "ahoj") even with error, it looks as wordpress is ignoring that.

How to solve it? The content is created by attached files - here: http://disk.kybernaut.cz/form.zip
It's really urgent. Thanks a lot