在ASP.NET中获取屏幕截图时出现“句柄无效”错误

当客户端用户单击按钮时，我尝试获取客户端用户的屏幕截图。

该代码在本地计算机上有效。但是，当我在服务器上发布时，该代码无效。我收到“句柄无效”错误。

我的错误在哪里？

using System;
using System.Data;
using System.Web;
using System.Web.UI;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Drawing;

public partial class Page: System.Web.UI.Page

{
    protected void Page_Load(object sender, EventArgs e) {...}

}

static string ImagePath;
public static void ScreenShot()
{


 foreach (Screen screen in Screen.AllScreens)
        {
            Bitmap bitmap = new Bitmap(screen.Bounds.Width, screen.Bounds.Height, PixelFormat.Format32bppArgb);

            using (Graphics graphics = Graphics.FromImage(bitmap))
            {
                graphics.CopyFromScreen(screen.Bounds.X, screen.Bounds.Y, 0, 0, screen.Bounds.Size, CopyPixelOperation.SourceCopy);
            }

            ImagePath= "/Screenshots/" + HttpContext.Current.Session["UserName"].ToString()+ " "+ DateTime.Now.ToString("dd.MM.yyyy HH.mm.ss");
            bitmap.Save(HttpContext.Current.Server.MapPath(ImagePath+ ".jpg"));
        }

}

   protected void btn_Click(object sender, EventArgs e)
   {
     ScreenShot(); 
   }