Not Initialized error on checkout

Hi,

I have a weird problem with the checkout form, when i fill in the form with Latin letters everything works as it should. But when i do the same thing, fill in firstname and lastname with Cyrillic letters and click on place order button, the form gives me Not Initialized error. Can you give me a hint on how to solve this issue or maybe the payment processor does not accept data in cyrillic, so i should not allow other input than latin?

Thanks for your time and help!