Web服务方法返回错误:“；“在生成XML文档时出现错误”；

在我的应用程序中，我使用了使用web服务的三层架构。我想在数据库中插入一个数据。当从Web服务调用insert方法时，它会给出一个错误："生成xml文档时出错

.CS保存点击事件

 protected void btnSave_Click(object sender, EventArgs e)
    {
        try
        {
             //assinging values to the Object(objEmp)
            string Result = objEmp.Insert();
            if (Result == "1")
            {
                Page.ClientScript.RegisterStartupScript(this.GetType(), "ShowMessage", string.Format("<script type='text/javascript'>alert('{0}')</script>", "Record Saved"));
                Response.Redirect("ViewEmployeeDetails.aspx");
            }
            else
            {
                Page.ClientScript.RegisterStartupScript(this.GetType(), "Error1", string.Format("<script type='text/javascript'>alert('{0}')</script>", Result.Replace("'", "'''")));
            }
        }
        catch (Exception ex)
        {
            Page.ClientScript.RegisterStartupScript(this.GetType(), "Error", string.Format("<script type='text/javascript'>alert('{0}')</script>", ex.Message.ToString()));
        }
    }

类别（Emp.cs）

public String Insert()
    {
        Service.SqlParameter[] param = new Service.SqlParameter[13];
        param[0] = new Service.SqlParameter();
        param[0].ParameterName = "@Dta_Users";
        param[0].Value = Dta_Users;
        param[0].SqlDbType = Service.SqlDbType.NVarChar;
        param[1] = new Service.SqlParameter();
        param[1].ParameterName = "@FK_EmployeeTypeID";
        param[1].Value = FK_EmployeeTypeID;
        param[1].SqlDbType = Service.SqlDbType.Decimal;
        param[2] = new Service.SqlParameter();
        param[2].ParameterName = "@EmployeeName";
        param[2].Value = EmployeeName;
        param[2].SqlDbType = Service.SqlDbType.NVarChar;
        param[3] = new Service.SqlParameter();
        param[3].ParameterName = "@CellNo";
        param[3].Value = CellNo;
        param[3].SqlDbType = Service.SqlDbType.NVarChar;
        param[4] = new Service.SqlParameter();
        param[4].ParameterName = "@PhNo";
        param[4].Value = PhNo;
        param[4].SqlDbType = Service.SqlDbType.NVarChar;
        param[5] = new Service.SqlParameter();
        param[5].ParameterName = "@Address";
        param[5].Value = Address;
        param[5].SqlDbType = Service.SqlDbType.NVarChar;
        param[6] = new Service.SqlParameter();
        param[6].ParameterName = "@Email";
        param[6].Value = Email;
        param[6].SqlDbType = Service.SqlDbType.NVarChar;
        param[7] = new Service.SqlParameter();
        param[7].ParameterName = "@DOB";
        if (DOB == null)
        {
            param[7].Value = DBNull.Value;
        }
        else
        {
            param[7].Value = DOB;
        }
        param[7].SqlDbType = Service.SqlDbType.DateTime;
        param[8] = new Service.SqlParameter();
        param[8].ParameterName = "@DOJ";
        param[8].Value = DOJ;
        param[8].SqlDbType = Service.SqlDbType.DateTime;
        param[9] = new Service.SqlParameter();
        param[9].ParameterName = "@DOR";
        param[9].Value = DOR;
        param[9].SqlDbType = Service.SqlDbType.NVarChar;
        param[10] = new Service.SqlParameter();
        param[10].ParameterName = "@Status";
        param[10].Value = Status;
        param[10].SqlDbType = Service.SqlDbType.NVarChar;
        param[11] = new Service.SqlParameter();
        param[11].ParameterName = "@Remarks";
        param[11].Value = Remarks;
        param[11].SqlDbType = Service.SqlDbType.NVarChar;
        param[12] = new Service.SqlParameter();
        param[12].ParameterName = "@Dta_User";
        param[12].Value = Dta_User;
        param[12].SqlDbType = Service.SqlDbType.NVarChar;
        return  s.InsUpdDel(Conn, "Employee_Insert", param);

    }

Web服务方法〔WebMethod〕

public string InsUpdDel(string Conn, string ProcName, SqlParameter[] p)
{
    try
    {
        using (SqlConnection cn = new SqlConnection(Conn))
        {
            if (cn.State == ConnectionState.Open || cn.State == ConnectionState.Broken || cn.State == ConnectionState.Connecting || cn.State == ConnectionState.Executing || cn.State == ConnectionState.Fetching)
                cn.Close();
            cn.Open();
            SqlCommand cmd = new SqlCommand(ProcName, cn);
            cmd.CommandType = CommandType.StoredProcedure;
            foreach (SqlParameter param in p)
            {
                cmd.Parameters.Add(param);
            }
            SqlDataReader dr = cmd.ExecuteReader();
            dr.Read();
            if (dr[0].ToString() == "1")
            {
                return "1";
            }
            else
            {
                return dr[0].ToString();
            }
            //dr.Close();
            cn.Close();
        }
    }
    catch (Exception ex)
    {
        return "Error : " + ex.Message.ToString();
    }

}

当我调试save_click事件时，光标转到catch语句。。。。因为错误来自web服务。如果我只是在Emp.cs中添加InsUpdDel（）方法，并在Insert（）中调用该方法，那么错误就不会出现

如果我写下面的代码，那么它给出的错误

        param[7] = new Service.SqlParameter();
        param[7].ParameterName = "@DOB";
        if (DOB == null)
        {
            param[7].Value = DBNull.Value;
        }
        else
        {
            param[7].Value = DOB;
        }
        param[7].SqlDbType = Service.SqlDbType.DateTime;

如果我写下面的代码，那么它不会给出错误

    param[7] = new Service.SqlParameter();
    param[7].ParameterName = "@DOB";
    param[7].Value = DOB;
    param[7].SqlDbType = Service.SqlDbType.DateTime;

param[7].Value = DBNull.Value;

param[7].Value = null;

foreach (SqlParameter param in p)
{
    if (param.Value == null)
    {
           param.Value = DBNull.Value;
    }
    cmd.Parameters.Add(param);
}