Cascading Dropdownlist not retreiving values

Hi All,

I cannot understand what's wrong with the below code but the dropdownlists are not populated as expected.

<asp:DropDownList ID="ddlcontinents" runat="server" CssClass="ddlcontent"></asp:DropDownList><cc1:CascadingDropDown ID="ccdddlcontinents" runat="server" 
        TargetControlID="ddlcontinents"
        PromptText="Select Continents"
        PromptValue=""
        ServicePath="ccdregioncountry.asmx"
        ServiceMethod="GetContinents"
        Category="Continent" /><asp:DropDownList ID="ddlcountries" runat="server"  CssClass="ddlcontent"> </asp:DropDownList><cc1:CascadingDropDown ID="ccdddlcountries" runat="server" 
        TargetControlID="ddlcountries"   
PromptText="Select Country"
PromptValue=""
ServicePath="ccdregioncountry.asmx"
ServiceMethod="GetCountries"
Category="Country"/>

I created a webmethod as follows:

Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration
Imports AjaxControlToolkit
Imports System.Collections.Generic<WebService([Namespace]:="http://tempuri.org/")> _<WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _<System.Web.Script.Services.ScriptService()> _
Public Class ccdregioncountry
    Inherits System.Web.Services.WebService
    Private conString As String = System.Configuration.ConfigurationManager.ConnectionStrings("DefaultConnection").ToString()<WebMethod> _
    Public Function GetContinents(knownContinentValues As String, Continent As String) As CascadingDropDownNameValue()
        Dim sqlConn As New SqlConnection(conString)
        sqlConn.Open()
        Dim sqlSelect As New SqlCommand("SELECT ContinentName, ContinentId FROM Continents", sqlConn)
        sqlSelect.CommandType = System.Data.CommandType.Text
        Dim sqlAdapter As New SqlDataAdapter(sqlSelect)
        Dim myDataset As New DataSet()
        sqlAdapter.Fill(myDataset)
        sqlConn.Close()
        Dim cascadingValues As New List(Of CascadingDropDownNameValue)()
        For Each dRow As DataRow In myDataset.Tables(0).Rows
            Dim ContinentId As String = dRow("ContinentId").ToString()
            Dim ContinentName As String = dRow("ContinentName").ToString()
            cascadingValues.Add(New CascadingDropDownNameValue(ContinentName, ContinentId))
        Next
        Return cascadingValues.ToArray()
    End Function<WebMethod> _
    Public Function GetCountries(knownContinentValues As String, Continent As String) As CascadingDropDownNameValue()
        Dim ContinentId As Integer
        Dim continentValues As StringDictionary = CascadingDropDown.ParseKnownCategoryValuesString(knownContinentValues)
        ContinentId = Convert.ToInt32(continentValues("Continent"))
        Dim sqlConn As New SqlConnection(conString)
        sqlConn.Open()
        Dim sqlSelect As New SqlCommand("SELECT CountryName, CountryId FROM Countries WHERE ContinentId=@ContinentId", sqlConn)
        sqlSelect.CommandType = System.Data.CommandType.Text
        sqlSelect.Parameters.Add("@ContinentId", SqlDbType.Int).Value = ContinentId
        Dim sqlAdapter As New SqlDataAdapter(sqlSelect)
        Dim myDataset As New DataSet()
        sqlAdapter.Fill(myDataset)
        sqlConn.Close()
        Dim cascadingValues As New List(Of CascadingDropDownNameValue)()
        For Each dRow As DataRow In myDataset.Tables(0).Rows
            Dim CountryId As String = dRow("CountryId").ToString()
            Dim CountryName As String = dRow("CountryName").ToString()
            cascadingValues.Add(New CascadingDropDownNameValue(CountryName, CountryId))
        Next
        Return cascadingValues.ToArray()
    End Function
End Class

Thank you in advance for  helping me out in double checking where is the error here.