I am trying to use a hyperlink in a grid view to download pdf files frm my database 2 my computer, Using a Guid when I click the hyperlink I get an error that says Guid should contain 32 digits...

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            
            switch (e.Row.RowType)
            {
               case DataControlRowType.DataRow:
                    FileSave fs = (FileSave)e.Row.DataItem;
                       switch (fs.contentType.ToLower())
                       {
                            case "image/pjpeg":
                            case "image/gif":
                            case "application/msword":
                            case "text/plain":
                                break;
                            default:
                                break;
                        }
                    HyperLink myLink = (HyperLink)e.Row.FindControl("lnkView");
            myLink.Enabled = true;
                       break;
                    }
            }

 public partial class DownloadFile : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (Request.QueryString.Get("ID") != null)
            {
                Response.Clear(); 
                 HERE IS THE ERROR                                                                        Guid ID = new Guid(Request.QueryString.Get("ID"));
                BLL.FileSave myFile = new BLL.FileSave();
                Response.ContentType = "application/x-uknown";
                Response.AppendHeader("Content_Disposition", "attachment; fileName=\"");
                if (myFile.containsFile)
                {
                    Response.BinaryWrite(myFile.fileData);
                }
                else
                {
                    Response.Redirect("~/");
                }

            }
        }
    }
}

public static FileSave GetItem(Guid ID)
        {
            FileSave myFile = null;
            csDAL objdal = new csDAL();
            IDataReader dr;
            dr = null;
            List<csParameterListType> objpar = new List<csParameterListType>();
            objpar.Add(new csParameterListType("@ID", SqlDbType.Int, ID));
            if (dr.Read())
            {
                myFile = new FileSave(dr);
            }
            dr.Close();
            return myFile ;
        }