下载的PDF文件无法打开

我通过以下代码在数据库中保存pdf文件

        string filename = Path.GetFileName(FileUpload1.PostedFile.FileName);
        string filetype = Path.GetExtension(FileUpload1.PostedFile.FileName);
        int filesize = FileUpload1.PostedFile.ContentLength;

        Stream fs = FileUpload1.PostedFile.InputStream;
        BinaryReader br = new BinaryReader(fs);
        byte[] content = br.ReadBytes((Int32)fs.Length);

        Objects.Insert_FilesToDatabase(filename, filetype, content,filesize);

，然后，我试图保存文件从数据库通过点击链接通过以下代码。

     void lnkDownload_Click(object sender, EventArgs e)
    {
        string filetype = Objects.GetFileType(Convert.ToInt32(txtslno.Text.Trim()));
        string filename=Objects.GetFileName(Convert.ToInt32(txtslno.Text.Trim()));
        int filesize = Objects.GetFileLength(Convert.ToInt32(txtslno.Text.Trim()));
        byte[] bytfile = new byte[filesize+1000];
        Response.Clear();
        Response.Buffer = true;
        Response.ContentType = "application/pdf";
        Response.AddHeader("content-disposition",attachment;filename="+filename+".pdf");
        Response.BufferOutput = true;
        Response.Charset = "";
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        Response.BinaryWrite(bytfile);
        Response.End();
    }

通过这段代码，我能够下载pdf文件，但我无法打开pdf文件。错误是文件没有正确解码。你能告诉我哪里做错了吗?

        byte[] bytfile = Objects.GetFile(Convert.ToInt32(txtslno.Text.Trim()));
        Response.Clear();
        Response.ClearContent();
        Response.ClearHeaders();
        Response.ContentType = "application/pdf";
        Response.AddHeader("Content-Disposition", "attachment;filename="+filename);
        Response.AddHeader("Content-Length", bytfile.Length.ToString());
        Response.OutputStream.Write(bytfile, 0, bytfile.Length);
        Response.Flush();
        Response.End();