webservice上传b64编码存图片问题，测试正常，页面调用就出错

[wanshichen]

[WebMethod]
 public void MsgBackAddOrModi(int InputPersonID, string Isyscode, string CreatDate, string CusClass, string CusID, string Photo0, string Photo1, string Photo2, string Photo3)
{
string dbcon = ConfigurationManager.ConnectionStrings["AucmaZDCoon"].ToString();
            SqlConnection conn = new SqlConnection(dbcon);
            DataSet ds = null;
 try
            {
                if (conn.State == ConnectionState.Closed)
                {
                    conn.Open();
                }

                string sqlproc = "spMsgBackAddOrModi";
                SqlCommand cmd = new SqlCommand(sqlproc, conn);
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.Add("@PersonID", SqlDbType.Int, 4);
                cmd.Parameters["@PersonID"].Direction = ParameterDirection.Input;
                cmd.Parameters["@PersonID"].Value = InputPersonID;
……
//执行存储
SqlDataAdapter da = new SqlDataAdapter(cmd);
                ds = new DataSet();
                da.Fill(ds);
int MsgBackID = Convert.ToInt32(ds.Tables[0].Rows[0][2].ToString());
 byte[] arr = Convert.FromBase64String(photo0);
MemoryStream ms = new MemoryStream(arr);
                Bitmap bmp = new Bitmap(ms);
string filename = DateTime.Now.ToString("yyyyMMddHHmmss") + Guid.NewGuid().ToString().Substring(0, 5) + ".jpg";
bmp.Save("F:\\Pic\\" + filename, System.Drawing.Imaging.ImageFormat.Jpeg);
string url = "http://localhost/WebTest/pic/" + filename;
//执行保存图片路径跟主表ID的存储
Context.Response.Charset = "GB2312"; //设置字符集类型  
                    Context.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
                    Context.Response.Write(“成功”);
}

现在是直接访问此webservice页面http://localhost/WebTest/ZDMsgBackInfoWS.asmx，此MsgBackAddOrModi方法，不会报错，会返回成功，写了一个test页面， temp.ZDMsgBackInfoWSSoapClient a = new temp.ZDMsgBackInfoWSSoapClient();
a.MsgBackAddOrModi(8023, "", "2015-12-14", "1", "1", Convert.ToBase64String(arr), null, null, null);
就会报错，提示：【从网络接收的xml存在问题。有关详细问题，请参见内部异常】
跟踪之后，发现异常是【根级别上的数据无效。 行 1,位置 1】，但是发布后，F5直接运行该webservice页面调用方法就不会报错，测试页面引用就会报错……求解答