This javascript shows and hides description (like alt in image tag). It works in IE but not in Mozilla, what is wrong please help:

[CODE=javascript]<SCRIPT LANGUAGE="JavaS cript">

// ############## SIMPLE BROWSER SNIFFER
if (document.layer s) {navigator.fami ly = "nn4"}
if (document.all) {navigator.fami ly = "ie4"}
if (window.navigat or.userAgent.to LowerCase().mat ch("gecko"))...