$(document).ready(
	function()
	{
	  var ddlValue = $("select.categorydropdown option:selected").val();
	  if (ddlValue == "multiple")
	  {
	    $('#selectMultipleBox').show();
	  }
	  
		$('select.categorydropdown').change(function () {
      var str =  $("select.categorydropdown option:selected").val();

		  if (str == "multiple"){
			  $('#selectMultipleBox').show('slow');
		  } else {  
		  	setTimeout('__doPostBack(\'cmtMain$ctl00$ddlEventCategories\',\'\')', 0);
		  }
        });

	}
);