[solvet] js - toogle in category

[eGzyl.pl]

i want make slide only in second ul in my category

i done:

   $('ul li ul li').click( function() {
  $(this).children('ul').toggle(); 
  if ((this).children('ul')){
  return false; 
   }
   else{return true;}
  });  

but i have one prolbem li in second ul dont open because return false what condition i must write do work??
if ((this).children('ul')) - its not work :<

SOLVET:

   $('ul.tree li ul li a').click( function() 
  { 
     if($(this).parent().children('ul')[0]) 
     {
      // $(this).parent().parent().children('li ul li').slideUp();
       if($(this).parent().children('ul').css('display')!='block') 
       {
          $('.active').slideUp();
          $('.active').removeClass('active');
          $(this).parent().children('ul').slideToggle(); 
          $(this).parent().children('ul').addClass('active');
       }
       return false; 
     }else
     {
       return true;  
     }
  }
  );