求救Cache问题,在线等候,请高手帮帮忙

Question

代码如下,请教高手,小弟在线等候,请帮帮忙,调试过程提示错误的位置已经设置成红色using System;
using System.Web;
using System.Web.Caching;
using System.Xml;
using System.Xml.XPath;/// <summary>
/// configProcess 的摘要说明
/// </summary>
namespace IOnhui.Config
{
    public static class SysConfig
    {
        private static XmlDocument configDoc = new XmlDocument();
        private static XmlElement configRoot;
        public static Cache OnhuiCache;
        /// <summary>
        /// 获取系统路径
        /// </summary>
        public static string systemPath
        {
            get
            {
                return HttpContext.Current.Request.PhysicalApplicationPath;
            }
        }        static SysConfig()
        {
            if (OnhuiCache["SystemConfig"] == null)
            {
                configDoc.Load(systemPath + "Core\\Config\\SystemConfig.xml");
                CacheDependency cacheDep = new CacheDependency(systemPath + "Core\\Config\\SystemConfig.xml");
                OnhuiCache.Add("SystemConfig", configDoc.DocumentElement, cacheDep, DateTime.MaxValue, TimeSpan.Zero, CacheItemPriority.High, null);            }
            configRoot = (XmlElement)OnhuiCache["SystemConfig"];
        }