Angive font-family ud fra selectboks

Hej!

Nedenstående kode skulle gerne ændre font-family på et span element, men gør det ikke.

Nogen der lige kan hjælpe?

<table>
<tr><td width="180" nowrap style="padding:6px;padding-left:7px"><strong>Skrifttype:</strong></td><td style="padding:6px"><select name="menu_font_family" onchange="document.getElementById('menu_font_f').innerHTML=this.options[this.selectedIndex].value;document.getElementById('menu_font_f').style.fontfamily=this.options[this.selectedIndex].value">
<option value="Arial, Helvetica, sans-serif">Arial, Helvetica, sans-serif</option>
<option value="Times New Roman, Times, serif">Times New Roman, Times, serif</option>
<option value="Courier New, Courier, mono">Courier New, Courier, mono</option>
<option value="Georgia, Times New Roman, Times, serif">Georgia, Times New Roman, Times, serif</option>
<option value="Verdana, Arial, Helvetica, sans-serif">Verdana, Arial, Helvetica, sans-serif</option>
<option value="Geneva, Arial, Helvetica, sans-serif">Geneva, Arial, Helvetica, sans-serif</option>
<option value="Tahoma, Arial, sans-serif">Tahoma, Arial, sans-serif</option>
</select></td><td width="100%"><span id="menu_font_f">Felt</span></td></tr>
</table>