script type="text/javascript"
function PAChange()
debugger
var ChangeSelect=document.getElementById("ddl_pachng").selectedIndex;
if((ChangeSelect==1) (ChangeSelect==2))
{
document.form1.txtpacd.disabled=false;
}
if(ChangeSelect==3)
{
document.form1.txtpacd.disabled=true;
}
}
script
////==================================call the above javascript inbody onload and dropdownlist change event
body onload="JavaScript:PAChange();"