Now it works fine! Thanks a lot to all for your help!
$(function(){ var state = 0; $('#navigation').mouseover( function() { if(state == 0) {$(this).animate({left: '0'}, 'slow'); state = 1;}} ); $('#navigation').mouseout( function() {if(state == 1) {$(this).animate({left: '-210'},'slow', function(){state = 0;});}} ); });