What is the way you want? Do you mean that it can't go fullscreen altogether or it's doing it in a specific way?

Hey thanks for reply but I could do it yesterday,my problem was about animation :)

With animation? I can only guess you're referring to the transition animation in going in and out of full screen? If so, then I assume this was changed in about:config by changing

• full-screen-api.transition-duration.enter
• full-screen-api.transition-duration.leave

both to 0 0. Anyways, glad to hear you found a solution.