Nestet layers i Netscape

jeg har følgende:
-------------------------------------
<div id=\"Layer1\" style=\"position:absolute; width:200px; height:115px; z-index:1; background-color: #990000; layer-background-color: #990000; border: 1px none #000000; left: 176px; top: 108px\">
  <div id=\"Layer4\" style=\"position:absolute; width:94px; height:81px; z-index:1; left: 27px; top: 11px; background-color: #00FF33; layer-background-color: #00FF33; border: 1px none #000000\"></div>
</div>
<div id=\"Layer2\" style=\"position:absolute; width:200px; height:115px; z-index:2; left: 470px; top: 115px; background-color: #FF0000; layer-background-color: #FF0000; border: 1px none #000000\">
  <div id=\"Layer3\" style=\"position:absolute; width:106px; height:91px; z-index:1; left: 29px; top: 16px; background-color: #990000; layer-background-color: #990000; border: 1px none #000000\"></div>
</div>-------------------------------------
Hvis man viser overstående i evt. NS4 - så viser det ikke den 2. div-gruppe. Hvorfor det?