我用SWFUpload自带的例子都不能上传文件！客户端一直报500错误，是什么原因，谢谢
错误如图所示


代码：
upload.aspx.cs文件内容：using System; 
using System.Data; 
using System.Configuration; 
using System.Collections; 
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; 
using System.IO; 
using System.Collections.Generic; 

public partial class upload : System.Web.UI.Page 
{ 
  protected void Page_Load(object sender, EventArgs e) 
  { 

System.Drawing.Image thumbnail_image = null; 
System.Drawing.Image original_image = null; 
System.Drawing.Bitmap final_image = null; 
System.Drawing.Graphics graphic = null; 
MemoryStream ms = null; 

try 
{ 
// Get the data 
HttpPostedFile jpeg_image_upload = Request.Files["Filedata"]; 

// Retrieve the uploaded image 
original_image = System.Drawing.Image.FromStream(jpeg_image_upload.InputStream); 

// Calculate the new width and height 
int width = original_image.Width; 
int height = original_image.Height; 
int target_width = 100; 
int target_height = 100; 
int new_width, new_height; 

float target_ratio = (float)target_width / (float)target_height; 
float image_ratio = (float)width / (float)height; 

if (target_ratio > image_ratio) 
{ 
new_height = target_height; 
new_width = (int)Math.Floor(image_ratio * (float)target_height); 
} 
else 
{ 
new_height = (int)Math.Floor((float)target_width / image_ratio); 
new_width = target_width; 
} 

new_width = new_width > target_width ? target_width : new_width; 
new_height = new_height > target_height ? target_height : new_height; 


// Create the thumbnail 

// Old way 
//thumbnail_image = original_image.GetThumbnailImage(new_width, new_height, null, System.IntPtr.Zero); 
// We don't have to create a Thumbnail since the DrawImage method will resize, but the GetThumbnailImage looks better 
// I've read about a problem with GetThumbnailImage. If a jpeg has an embedded thumbnail it will use and resize it which 
// can result in a tiny 40x40 thumbnail being stretch up to our target size 


final_image = new System.Drawing.Bitmap(target_width, target_height); 
graphic = System.Drawing.Graphics.FromImage(final_image); 
graphic.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, target_width, target_height)); 
int paste_x = (target_width - new_width) / 2; 
int paste_y = (target_height - new_height) / 2; 
graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; /* new way */ 
//graphic.DrawImage(thumbnail_image, paste_x, paste_y, new_width, new_height); 
graphic.DrawImage(original_image, paste_x, paste_y, new_width, new_height); 

// Store the thumbnail in the session (Note: this is bad, it will take a lot of memory, but this is just a demo) 
ms = new MemoryStream(); 
final_image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); 

// Store the data in my custom Thumbnail object 
string thumbnail_id = DateTime.Now.ToString("yyyyMMddHHmmssfff"); 
Thumbnail thumb = new Thumbnail(thumbnail_id, ms.GetBuffer()); 

// Put it all in