onMouseOver mit Buttons in Tabelle funktioniert nicht

[Tim]

Anstelle von L1-2news.jpg wird main.jpg verändert:

<script type="text/javascript">
<!--
Normal1 = new Image();
Normal1.src = "Bildelemente/L1-2news.jpg";     /* erste Standard-Grafik */
Highlight1 = new Image();
Highlight1.src = "Bildelemente/L1-2news-h.jpg"; /* erste Highlight-Grafik */

function Bildwechsel(Bildnr,Bildobjekt) {
 window.document.images[Bildnr].src = Bildobjekt.src;
}
//-->
</script>
<center>
<table border="0" cellspacing="0" cellpadding="0" width="600" rules="none" >
<colgroup>
<col width="600">
</colgroup>
<tr>
 <td><th colspan="5"><img src="Bildelemente/main.jpg" width="600" height="115" border="0" alt=""></th></td>
</tr>
</table>
<table border="0" cellspacing="0" cellpadding="0" width="600" rules="none" >

<colgroup>
<col width="40">
<col width="105">
<col width="230">
<col width="195">
<col width="30">
</colgroup>
<tr>
 <td><img src="Bildelemente/L1-1.jpg" width="40" height="35" border="0" alt=""> </td>
 <td><a href="" onMouseOver="Bildwechsel(0,Highlight1)"
   onMouseOut="Bildwechsel(0,Normal1)"><img src="Bildelemente/L1-2news.jpg" width="105" height="35" border="0" alt="News"></a></td>
 <td> <img src="Bildelemente/L1-3.jpg" width="230" height="35" border="0" alt=""></td>
 <td> <img src="Bildelemente/L1-4gb.jpg" width="195" height="35" border="0" alt=""></td>
 <td><img src="Bildelemente/L1-5.jpg" width="30" height="35" border="0" alt=""> </td>
</tr>
</table>