Checkbox Tree bug under IE6

userPollTreePanel.on('beforeexpandnode', function(node, deep, anim) {
		if (node.attributes.isGroup == '1') {
			var isIE = !!window.ActiveXObject;   
 			var isIE6 = isIE && !window.XMLHttpRequest;
 			if(isIE6){
 				var logicChannelsSelected = userPollTreePanel.getChecked();
				var logicChannelRecordArr  = [];
				for (var i = 0; i < logicChannelsSelected.length; i++) {
					var id = logicChannelsSelected[i].id;
					logicChannelRecordArr.push(id);
				}
				for(var j=0;j<node.childNodes.length;j++){
					for(var k=0;k<logicChannelRecordArr.length;k++){
						if(logicChannelRecordArr[k]==node.childNodes[j].attributes.id){
	        				node.childNodes[j].getUI().checkbox.indeterminate = true;
							break;
						}
					}
				}
 			}
			node.getUI().getIconEl().src = '../../ext/resources/images/default/tree/folder-open.gif';
		}
	});