display: none funktioniert nicht in einer (Selfhtml-)NaviLeiste

[maybe]

!!Richtige Version!!
So jetzt ist der Code valide, Kleiner Fehler behoben. (li:hover ul)

  
body {  
	background-image:url(images/hintergrund.gif)  
	  
	}  
#seite  { 			/*Zentraler Tag für die mittige Zentrierung*/  
	text-align: left;  
	margin: 0 auto;	/* standardkonforme horizontale Zentrierung */  
	width: 800px;  
	padding: 1em;  
	background-color:#ffffff;  
	min-height: 1050px;  
	}  
#seite div {  
	}  
#titel {  
	width: 100%;  
	background-color:#ffffff;  
	text-align: center;  
	}  
#menu{  
	width: 170px;  
	margin-top:50px;  
	float: left;  
	}  
ul#Navigation {  
	float: left;  
	width: 170px;  
	margin: 0; padding: 1px;  
	background-color: #616a2b;  
	}  
ul#Navigation li {  
    list-style: none;  
	width: 160px;  
	float: left;  
	position: relative;  
	margin: 3px;  
	margin-left: 5px;  
	padding: 0;  
	}  
*:first-child+html ul#Navigation li {  /* Korrektur fuer den IE 7 */  
    margin-bottom: -0.1em;  
	}  
ul#Navigation li  ul {  
	list-style: none;  
	margin: 0;  
	padding: 0;  
	position: absolute;  
	top: 1.6em;  
	left: -1em;  
	display: none;  
	}  
u#Navigation li:hover ul {  
	display:block;  
	}  
ul#Navigation li ul li {  
	list-style: none;  
	width: 160px;  
	float:none;  
	display:block;  
	margin-bottom: 2px;  
	}  
ul#Navigation  a {  
    display:block;  
    color:#eadd88;  
    font-size:20px;  
    font-family:"Bookman Old Style";  
    font-weight: normal;  
    text-decoration:none;  
    background-color: #424421;  
    text-align: center;  
    width:160px;  
    height:25px;  
    }  
ul#Navigation a:hover {  
    color: #424421;  
    background-color: #eadd88;  
	}  
ul#Navigation a:active {  
    color:#000000;  
    background-color: #424421;  
	}  
ul#Navigation span {  
	display:block;  
	font-size:20px;  
	font-family:"Bookman Old Style";  
	color:#424421;  
	background-color:#eadd88;  
	text-align: center;  
	}  
#Info {  
	margin-top:50px;  
	float: right; width: 130px;  
	margin: 0; padding: 5px;  
	border: 1px solid silver;  
	}  
#Info p {  
	margin: 0;  
	}  
#text {  
	margin-left: 174px;  
	margin-top: 50px;  
	border: 1px solid silver;  
	width: 478px;  
	}	  
#text p {  
	font-family: arial;  
	text-align:left;  
	margin: 1em;  
	color:#000000;  
	}  
img {  
	border: 0;  
	}  
	  
  

Geholfen hats aber nichts :(