Cascading combo box not working

[bittsman]

i am a newbbie am trying to have 3 cascading comboboxes for Country, State and City all contained in a 3 tables in Ms Access Database and related via foreign keys. When the country combobox is has a selected the other two will show the relevant state and cities for that country selected. in the meantime the first combobox is the one populating the countries and nothing for the State and cities. please help
the code is as follows:

Imports System.Data
Imports System.Configuration
Imports System.Data.OleDb
 
Public Class Form1
    Dim strConn As String = "Provider= Microsoft.Ace.Oledb.12.0; Data source =" & Environment.CurrentDirectory & "\Practice_Country_combo1.accdb"
    Dim cn As New OleDbConnection(strConn)
    Dim Cmd As OleDbCommand
    Private Sub Form1_Load_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        LoadCountry()
    End Sub
    Private Sub LoadCountry()
        Using cn As New OleDbConnection(strConn)
            Using cmd As New OleDbCommand()
                Try
                    With cmd
                        .Connection = cn
                        .CommandType = CommandType.Text
                        .CommandText = "SELECT CountryID, Country FROM Country"
                    End With
                    Dim ds As New DataSet()
                    Dim da As New OleDbDataAdapter()
                    da.SelectCommand = cmd
                    cn.Open()
                    da.Fill(ds)
                    cn.Close()
                    ComboBox1.ValueMember = "CountryID"
                    ComboBox1.DisplayMember = "Country"
                    ComboBox1.DataSource = ds.Tables(0)
                Catch ex As Exception
 
                End Try
            End Using
        End Using
    End Sub
 
    Private Sub LoadProvince(ByVal countryID As Integer)
        Using cn As New OleDbConnection(strConn)
            Using Cmd As New OleDbCommand()
                Try
                    With Cmd
                        .Connection = cn
                        .CommandType = CommandType.Text
                        .CommandText = "SELECT ProvinceID, Province FROM Province WHERE CountryID =?"
                    End With
                    Cmd.Parameters.AddWithValue("?CountryID", OleDbType.Integer)
                    Dim ds As New DataSet()
                    Dim da As New OleDbDataAdapter()
                    da.SelectCommand = Cmd
                    cn.Open()
                    da.Fill(ds)
                    cn.Close()
                    If ds.Tables(0).Rows.Count > 0 Then
                        ComboBox2.ValueMember = "ProvinceID"
                        ComboBox2.DisplayMember = "Province"
                        ComboBox2.DataSource = ds.Tables(0)
                    End If
                Catch ex As Exception
 
                End Try
            End Using
        End Using
    End Sub
 
    Private Sub LoadCity(ByVal ProvinceID As Integer)
        Using cn As New OleDbConnection(strConn)
            Using cmd As New OleDbCommand()
                Try
                    With cmd
                        .Connection = cn
                        .CommandType = CommandType.Text
                        .CommandText = "SELECT CityID, City FROM City WHERE ProvinceID =?"
                    End With
                    cmd.Parameters.AddWithValue("?ProvinceID", OleDbType.Integer)
                    Dim ds As New DataSet()
                    Dim da As New OleDbDataAdapter()
                    da.SelectCommand = cmd
                    cn.Open()
                    da.Fill(ds)
                    cn.Close()
                    If ds.Tables(0).Rows.Count > 0 Then
                        ComboBox3.DataSource = ds.Tables(0)
                        ComboBox3.DisplayMember = "City"
                        ComboBox3.ValueMember = "CityID"
                    End If
                Catch ex As Exception
 
                End Try
            End Using
        End Using
    End Sub
 
    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
        If ComboBox1.SelectedValue.ToString() <> "" Then
            Dim CountryID As Integer = Convert.ToInt32(ComboBox1.SelectedValue.ToString())
            LoadProvince(CountryID)
            ComboBox3.SelectedIndex = 0
        End If
    End Sub
 
    Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
        Dim ProvinceID As Integer = Convert.ToInt32(ComboBox2.SelectedValue.ToString())
        LoadCity(ProvinceID)
    End Sub
 
 
 
End Class

[SioSio]

In Subroutine LoadProvince()

With Cmd
  .Connection = cn
  .CommandType = CommandType.Text
  .CommandText = "SELECT ProvinceID, Province FROM Province WHERE CountryID =" & comboBox1.SelectedValue.ToString
End With

And
In SUbroutine LoadCity()

With cmd
  .Connection = cn
  .CommandType = CommandType.Text
  .CommandText = "SELECT CityID, City FROM City WHERE ProvinceID =" & comboBox2.SelectedValue.ToString
End With