Providing Link For Document/pdf/zip

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C#

ASP.NET

In My Page I have Used Link Button. On Click of that link button I am redirecting user to
Corresponding Address where data is saved
But Its working only in chrome
in Firefox the extension of File is always .aspx

So Basically what i want to ask is this Coding Error or problem of browser
Updated I have Checked in Firebug and didn't find any error.

My Code is

 tenderDetail = BLLTender.GetTenderDetail(long.Parse(Request.QueryString["TenderID"]));
 var FileName = tenderDetail.TechDoc;
if (File.Exists(Server.MapPath("Document/" + FileName)))
 {
     var path = Server.MapPath(Server.MapPath("Document/" + FileName));
     var Extension = Path.GetExtension(path);
     var client = new WebClient();
     var buffer = client.DownloadData(path);
     switch (Extension)
     {
         case ".docx":
         case ".doc":
             Response.ContentType = "Application/msword";
             Response.AddHeader("content-length", buffer.Length.ToString(CultureInfo.InvariantCulture));
             Response.BinaryWrite(buffer);
             break;
         case ".xlsx":
         case ".xls":
             Response.ContentType = "Application/x-msexcel";
             Response.AddHeader("content-length", buffer.Length.ToString(CultureInfo.InvariantCulture));
             Response.BinaryWrite(buffer);
             break;
         case ".pdf":
             Response.ContentType = "application/pdf";
             Response.AddHeader("content-length", buffer.Length.ToString(CultureInfo.InvariantCulture));
             Response.BinaryWrite(buffer);
             break;
         case ".zip":
         case ".rar":
             Response.ContentType = "application/zip";
             Response.AddHeader("content-length", buffer.Length.ToString(CultureInfo.InvariantCulture));
             Response.BinaryWrite(buffer);
             break;
     }
 }

After Searching on net I have found i should create a page on which i provide downloading link
so i change my code to this but still in case of .xls in firefox it comes with unknown extension

var fileName = Request.QueryString["name"];
Response.Clear();
// Clear the content of the response
Response.ClearContent();
Response.ClearHeaders();

// Buffer response so that page is sent
// after processing is complete.
Response.BufferOutput = true;
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
Response.TransmitFile(Server.MapPath("~/Document/" + fileName));
Response.End();