检索LookupValues，Javascript SharePoint 2013，不工作

var context = new SP.ClientContext.get_current();

var list = context.get_web().get_lists().getByTitle('列表名称');

var query = new SP.CamlQuery();
query.set_viewXml('<View><Query><Where><Eq><FieldRef Name=\'ID\'/><Value Type=\'Number\'>1</Value></Eq></Where></Query></View>');

var items = list.getItems(query);
context.load(items);

context.executeQueryAsync(
    function(){
        var enumerator = items.getEnumerator();
        while (enumerator.moveNext()) {
            var item = enumerator.get_current();
            var lookupValue = item.get_item('Lookup字段名称');
            // 处理获取到的Lookup字段的值
        }
    },
    function(sender, args){
        console.log(args.get_message());
    }
);