I'm getting a SystemArgument.Exception when I try to pass the parameters to the WebMethod, which is part of the data: option of the jQuery .ajax call...

## code from aspx.cs

public partial class login : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    [WebMethod(EnableSession = true)]
    public static User VerifyLogin(string sEmail, string sPassword)
    {

      TempusEntities context = new TempusEntities();

      var query = context.Users.FirstOrDefault(u => u.Email == sEmail && u.Password == sPassword);

      if (query != null)
      {
        HttpContext.Current.Session.Add("User", (User)query);
        return (User)query;
      }
      else
        return null;

    }
}

## JavaScript from aspx page

<script type="text/javascript">
      $(document).ready(function () {
          // Add the page method call as an onclick handler for the div.


          $("#loginfailed").dialog({ autoOpen: false, modal: true, buttons: { "Ok": function () { $(this).dialog("close"); } } });


      });

      $("#btnLogin").click(function () {
                    var email = $('#txtEmail').text;
                    var passwd = $('#txtPassword').text;
                    $.ajax({
                        type: "POST",
                        url: "login.aspx/VerifyLogin",
                        data: "{ sEmail:" + $('#txtEmail').text + "," + "sPassword: " + $('#txtPassword').text + "}",
                        contentType: "application/json; charset=utf-8",
                        dataType: "json",
                        success: LoginSuccess,
                        error: LoginFailed
                    });
                });
      function LoginSuccess(data) {
          window.location('index.aspx?user=' + data.d.hasOwnProperty('UserId'));
      }

      function LoginFailed() {
          $("#loginfailed").dialog('open');

      }