这么为什么无法获得表单数据

<!--javascript部分>

<script type="text/javascript">

            function OnUpLoad() {

               

                var Uname = document.getElementById("ItId").value;

                var Una = document.getElementById("ItName").value;

                var Un = document.getElementById("StreentAddress").value;

             

                    alert(Uname+Una+Un);   //正常的

    

                document.getElementById("F1").submit();

            }

        </script>

<!--html部分-->

 <form  id="F1" action="Handler.ashx" method="get">

        <table>

            <tbody>

                <tr><td><label>Id</label><td>

                    <td><input type="text" id="ItId"/></td>

                

                </tr>

                <tr>

                    <td><label>Name:</label></td>

                   <td> <input type="text" id="ItName" /></td>

                </tr>

               <tr> 

                   <td>Address:</td>

                   <td> <input type="text" id="StreentAddress" /></td>

               </tr>

               <tr> 

                   <td>

                    <input type="button" value="提交" onclick="OnUpLoad()" id="But1"/>

                    <td>

               </tr>

                </tbody>

         </table>

    </form>

 int er = 0;

        string strId = context.Request.Form["ItId"]; //这里就没有数据的了

        string strName = context.Request.Form["ItName"];

        string strStreentAddress = context.Request.Form["StreentAddress"];

        int id = Convert.ToInt32(strId);

        using (SqlConnection SqlC = new SqlConnection("Data Source=.;Initial Catalog=db_2008;Integrated Security=True"))

        {

            SqlC.Open();

            SqlCommand Sc = SqlC.CreateCommand();

            Sc.CommandText = "INSERT INTO A values(@id,@name,@Address)";

            SqlParameter[] SP = { new SqlParameter("@id", id), new SqlParameter("@name", strName), new SqlParameter("@Address", strStreentAddress) };

            Sc.Parameters.AddRange(SP);

            er = Sc.ExecuteNonQuery();

            SqlC.Close();