Problem with tell_a_friend module

I created on template a standard form using example from documentation: http://ellislab.com/expressionengine/user-guide/modules/email/tellafriend.html

But it’s not always works. I’m using also a Structure extension and “tell a friend” form works correctly only for pages with selected parents. When i select NONE as a parent, the only thing what i see after click “tell a friend” button is a blank modal. There is no html form code at all in source.

Here’s example:http://fota.fota-kager.pl/partnerzy/ (click “Poleć znajomemu” link to activate tell a friend form).

And here’s the same code, but that page has a parent: http://fota.fota-kager.pl/oferta/czesci_zamienne/

As you can see, on second link, it works… When i move a page from first example in Structure to another page as a children, it works too…

Can someone help me in this matter?

Thanks.