记数器程序 运行老出错!该怎么处理

记数器程序 运行老出错!!!
代码如下:
using   System;
using   System.Data;
using   System.Configuration;
using   System.Web;
using   System.Web.Security;
using   System.Web.UI;
using   System.Web.UI.WebControls;
using   System.Web.UI.WebControls.WebParts;
using   System.Web.UI.HtmlControls;

public   partial   class   _Default   :   System.Web.UI.Page  
{
        protected   void   Page_Load(object   sender,   EventArgs   e)
        {
                int   Counter;
                Application.Lock();
                //锁定，不允许其他用户修改变量
                Application.Set( "Counter ",   Application.Count   +   1);
                //访问计数增加
                Application.UnLock();
                //开锁，允许其他用户修改变量
                MyCounter.Text   =   "您是第 "   +   Application.Count   +   "   位访客 ";

        }
}

------解决方案--------------------
代码写在Global.asax.cs里面：
protected void Application_Start(Object sender, EventArgs e)
{
Application[ "Counter "] = 0;
}

protected void Session_Start(Object sender, EventArgs e)
{
Application.Lock();
Application[ "Counter "] = Convert.ToInt32(Application[ "Counter "]) + 1;
Application.UnLock();
}

给的分太少了，所以以上代码我没测试...