function populateSubTopicControl(url, primaryTopic, control_id, topicSelected){
		jQuery(control_id).empty();
		jQuery(control_id).append('<option value="NONE" selected="selected">-- Select Sub Topic --</option>');
		jQuery(control_id).val('NONE');
		
		if (primaryTopic == 'NONE')
			return;
		
		jQuery.ajax({
		type: "POST",
		url: url + primaryTopic,
		success: 
			function(jsonString) {
				
				try{ 
					jsonString = jsonString.replace(/<!--\s\d+\.\d+s\s-->/, '');						
					var jsonObj = JSON.parse(jsonString);
				  
					for(var i = 0; i < jsonObj.Topics.length; i++)
						jQuery(control_id).append('<option value="' + jsonObj.Topics[i].topic_key + '">' + jsonObj.Topics[i].topic_name + '</option>');
					
					if (topicSelected != null) {
					   jQuery(control_id).val(topicSelected);
					} else
					  jQuery(control_id).val('NONE');
					
				} catch(e){
          window.console.log(e);
				}
			
			}
		});
}