水平太差，虽然认为Linq是个好东东，但有谁能教教我，怎么调试？

想做个通过XML做配置的方案，使用Linq

<?xml version="1.0" encoding="utf-8"?>
<root>
    <schedules>
        <idle>3600000</idle>
        <schedule>
            <dic>e:\</dic>
            <schedulename>dhdp</schedulename>
            <configfile>dhdpconfig.xml</configfile>
        </schedule>
        <schedule>
            <dic>e:\</dic>
            <schedulename>logdhdp</schedulename>
            <configfile>logdhdpconfig.xml</configfile>
        </schedule>
    </schedules>
</root>

class Schedule 
    {
        public string dic { get; set; }
        public string schedulename { get; set; }
        public string configfile { get; set; }
    }
    class Schedules
    {
        public int Idle { get; set; }
        public List<Schedule> ScheduleList { get; set; }        
    } 

    class Program
    {
        static void Main(string[] args)
        {
            
            var xmlfn = @"Schedules.xml";        
            TestScheduleList(xmlfn);
            TestSchedulesList(xmlfn);
            TestSchedulesList2(xmlfn);
            Console.ReadKey();
        }
        public static void TestScheduleList(string xmlfn)
        {
            XElement SchedulesXml = XElement.Load(xmlfn);

            List<Schedule> ScheduleList = (
                from ScheduleElement in SchedulesXml.Elements("schedules").Descendants("schedule")
                select new Schedule
                {
                    dic = ScheduleElement.Element("dic").Value,
                    schedulename = ScheduleElement.Element("schedulename").Value,
                    configfile = ScheduleElement.Element("configfile").Value                   
                }
            ).ToList();
            Console.WriteLine("测试ScheduleList");
            foreach (var sc in ScheduleList)
            {
                Console.WriteLine(sc.configfile);
            }
            Console.ReadKey();
        }
        public static void TestSchedulesList(string xmlfn)
        {
            XElement SchedulesXml = XElement.Load(xmlfn);
            var SchedulesList = from SchedulesElement in SchedulesXml.Elements("schedules")
                                select SchedulesElement;
            Console.WriteLine("测试SchedulesList");
            foreach (var scs in SchedulesList)
            {
                Console.WriteLine(scs.Value);
            }
            Console.ReadKey();
        }
        public static void TestSchedulesList2(string xmlfn)
        {
            XElement SchedulesXml = XElement.Load(xmlfn);
            var SchedulesList = from SchedulesElement in SchedulesXml.Elements("schedules")
                                select new Schedules
                                {
                                    Idle = (int)SchedulesElement.Element("Idle"),
                                    ScheduleList = (
                                        from ScheduleElement in SchedulesElement.Descendants("schedule")
                                        select new Schedule
                                        {
                                            dic = ScheduleElement.Element("dic").Value,
                                            schedulename = ScheduleElement.Element("schedulename").Value,
                                            configfile = ScheduleElement.Element("configfile").Value                                           
                                        }
                                     ).ToList()
                                };
            Console.WriteLine("测试SchedulesList");
            foreach (var scs in SchedulesList)
            {
                Console.WriteLine(scs.ScheduleList.ToString());
            }
            Console.ReadKey();
        }
    }
 
 

在使用TestSchedulesList2有错误，不知怎样调试，错误如下：

未处理 System.ArgumentNullException
  Message="值不能为空。\r\n参数名: element"
  Source="System.Xml.Linq"
  ParamName="element"
  StackTrace:
       在 System.Xml.Linq.XElement.op_Explicit(XElement element)
       在 ConsoleApplication1.Program.<TestSchedulesList2>b__7(XElement SchedulesElement) 位置 D:\web\ConsoleApplication1\ConsoleApplication1\Program.cs:行号 170
       在 System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
       在 ConsoleApplication1.Program.TestSchedulesList2(String xmlfn) 位置 D:\web\ConsoleApplication1\ConsoleApplication1\Program.cs:行号 186
       在 ConsoleApplication1.Program.Main(String[] args) 位置 D:\web\ConsoleApplication1\ConsoleApplication1\Program.cs:行号 129
       在 System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       在 System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       在 Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       在 System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       在 System.Threading.ThreadHelper.ThreadStart()
  InnerException:

经过大家的提醒，终于找到原因了，XML是要区分大小写的，我将idle写成了Idle了，改后运行正常了。

public static void TestSchedulesList2(string xmlfn)
        {
            XElement SchedulesXml = XElement.Load(xmlfn);
            var SchedulesList = from SchedulesElement in SchedulesXml.Elements("schedules")
               select new Schedules
                {
                    Idle = int.Parse(SchedulesElement.Element("idle").Value),
                    ScheduleList =
                        (from ScheduleElement in SchedulesElement.Descendants("schedule")
                            select new Schedule
                            {
                                dic = ScheduleElement.Element("dic").Value,
                                schedulename = ScheduleElement.Element("schedulename").Value,
                                configfile = ScheduleElement.Element("configfile").Value
                             }
                         ).ToList()
                };
            Console.WriteLine("测试SchedulesList");
            foreach (var scs in SchedulesList)
            {
                Console.WriteLine(scs.ScheduleList[0].schedulename);
            }
            Console.ReadKey();
        }