About Drop down List

Question

Hi   Guys   

 

Please Help me i am getting this error  whenever i am selecting any data from drodown lisy

 

[WebMethod]

public static List<ListItem> GetClassgrp()

{

string query = "select CODE,DESC_E from S_CLASS_GRP Order By 1";

string connectionstring = ConfigurationManager.ConnectionStrings["constrIND"].ConnectionString;

using (OracleConnection con = new OracleConnection(connectionstring))

{

using (OracleCommand cmd = new OracleCommand(query))

{

List<ListItem> classgrp = new List<ListItem>();

cmd.CommandType = CommandType.Text;

cmd.Connection = con;

con.Open();

using (OracleDataReader sdr = cmd.ExecuteReader())

{

while (sdr.Read())

{

classgrp.Add(new ListItem

{

Value = sdr["CODE"].ToString(),

Text = sdr["DESC_E"].ToString()

});

}

}

con.Close();

return classgrp;

}

}

}

 

and this method i am calling by JQuery Ajax

 

$.ajax({

type: "POST",

url: "DropDwonPopulate.aspx/GetClassgrp",

data: '{}',

contentType: "application/json; charset=utf-8",

dataType: "json",

success: function (r) {

var ddlCLG = $("[id*=ddlCLG]");

ddlCLG.empty().append('<option selected="selected" value="%">All</option>');

$.each(r.d, function () {

ddlCLG.append($("<option></option>").val(this['Value']).html(this['Text']));

});

}

});

 and this is my error