jQuery datatables refresh data not working

i can use server side to fill datatables and other working that but i cant refresh data after clicking on `reload_table` element.clear datatable is work correctly but draw not working.

	$('#reload_table').live('click',function(){
	   oTable_topics.fnReloadAjax(oTable_topics.fnSettings());
	   oTable_topics.fnClearTable();
	   oTable_topics.fnDraw();
        $.ajax({
           url: "server_processing.php",
           success: function() {
               // if it worked, ask datatable to redraw the table with the new data
               $("#showTopics").dataTable().fnDraw();
               // if this js function does anything useful (like deleting the row), then call it:
               Success();
           },
           error: function() {
               // display any error (like server couldn't be reached...), or at least try to log it
           }
          });
	});
    oTable_topics =$('#showTopics').dataTable({
    	    "bLengthChange": false,
    	    "iDisplayLength": 12,                               
    	    "bScrollCollapse": true,       
    	    "bJQueryUI": true,
    	    "bAutoWidth": false,
    	    "sAjaxSource": "server_processing.php",
    		"sPaginationType": "full_numbers",
    		"bProcessing": true,

    	 	"fnDrawCallback": function(oSettings) {
                clickRowHandler_topics();
    			if ( oSettings.aiDisplay.length == 0 )
    			{
    				return;
    			}		                
    			var nTrs = $('tbody tr', oSettings.nTable);
    			var iColspan = nTrs[0].getElementsByTagName('td').length;
    			var sLastGroup = "";
    			for ( var i=0 ; i<nTrs.length ; i++ )
    			{
    				var iDisplayIndex = oSettings._iDisplayStart + i;
    				var sGroup = oSettings.aoData[ oSettings.aiDisplay[iDisplayIndex] ]._aData[0];
    				if ( sGroup != sLastGroup )
    				{
    					var nGroup = document.createElement( 'tr' );
    					var nCell = document.createElement( 'td' );
    					nCell.colSpan = iColspan;
    					nCell.className = "group";
    					nCell.innerHTML = sGroup;
    					nGroup.appendChild( nCell );
    					nTrs[i].parentNode.insertBefore( nGroup, nTrs[i] );
    					sLastGroup = sGroup;
    				}
    			}
    		},
    		"aoColumnDefs": [
    			{ "bVisible": false, "aTargets": [ 0 ] }
    		],
    		"aaSortingFixed": [[ 0, 'asc' ]],
    		"aaSorting": [[ 1, 'asc' ]],
    	 	"fnServerParams": function ( aoData ) {
    	      aoData.push(
    			 {"name": "id"   ,      "value": "i.id" },	      	
     			 {"name": "subject"   , "value": "i.subject" },
    			 {"name": "date_time",  "value": "i.date_time"} ,
    			 {"name": "posted_by",  "value": "u.username"} ,
    			 {"name": "ctitle"   ,  "value": "c.title"} ,
    			 {"name": "etitle"   ,  "value": "e.title"},
    			 {"name": "istatus"   ,  "value": "i.status"},
    			 {"name": "join"     ,  "value": "JOIN categories c ON i.category = c.id JOIN status_topics e ON i.status = e.id JOIN users u ON i.posted_by = c.id"},
    			 {"name": "action"   ,  "value": "topics" }
    	      )}
    		});