Error when checking checkbox property

I want to show div if checkbox is checked. If not, I want to hide it. Here is my code, but it doesn't work.

$(".formularz_zgloszeniowy .firma input[type='checkbox']").change(function() {
    if(this.checked) {
        $(".formularz_zgloszeniowy .formularz_firma").css('display'​​​​​​​​​​​​​​​​​​​​​​​​​​​,'block');​​​​​​
    } 
    else 
    {
      $(".formularz_zgloszeniowy .formularz_firma").css('display'​​​​​​​​​​​​​​​​​​​​​​​​​​​,'none');​​​​​​
    }
}); 

I'm getting this error:

Uncaught SyntaxError: missing ) after argument list