Custom theme, contact form 7 & fast secure form doesn’t work

I found the solution myself,

It had something to do with my code echoing out

$content = $page->post_content
... echo $content;...

I changed this to

$content = apply_filters('the_content', $page->post_content);
... echo $content;...

And now it works!

Ref: https://stackoverflow.com/questions/6405974/using-get-pages-in-wordpress-is-stripping-out-my-p-tags