problema con DropDownlist dependientes

[Sayra]

Hola y si lo haga asi se cargan los tres drop, pero el drop2 no me deja seleccionar los item de ciudad que muestra,

Sub Page_Load(Sender As Object, E As EventArgs)

If Not IsPostBack

Dim ds As DataSet
Dim MyConnection As SqlConnection
Dim MyCommand As SqlDataAdapter

ds = New DataSet ()
MyConnection = New SqlConnection("SERVER=MDS01; DATABASE=be; INTEGRATED SECURITY=false;PASSWORD=sa;USER=sa")

MyCommand = New SqlDataAdapter ("select EstadoID, Nombre_Estado from Estado", MyConnection)
MyCommand.Fill(ds,"Estado")

DropDownList1.DataSource = ds.Tables("Estado").DefaultView
DropDownList1.DataTextField = "Nombre_Estado"
DropDownList1.DataValueField ="EstadoID"
DropDownList1.DataBind()
end if

Dim dc As DataSet
Dim MyConnection2 As SqlConnection
Dim MyCommand2 As SqlDataAdapter

dc = New DataSet ()
MyConnection2 = New SqlConnection("SERVER=MDS01; DATABASE=be; INTEGRATED SECURITY=false;PASSWORD=sa;USER=sa")

MyCommand2 = New SqlDataAdapter ("select CiudadID, Nombre_Ciudad from Ciudad Where EstadoID=" &DropDownList1.SelectedItem.Value, MyConnection2)
MyCommand2.Fill(dc,"Ciudad")

DropDownList2.DataSource = dc.Tables("Ciudad").DefaultView
DropDownList2.DataTextField = "Nombre_Ciudad"
DropDownList2.DataValueField ="CiudadID"
DropDownList2.DataBind()


Dim du As DataSet
Dim MyConnection3 As SqlConnection
Dim MyCommand3 As SqlDataAdapter

du = New DataSet ()
MyConnection3 = New SqlConnection("SERVER=MDS01; DATABASE=be; INTEGRATED SECURITY=false;PASSWORD=sa;USER=sa")

MyCommand3 = New SqlDataAdapter("select UbicacionID, Descripcion from Ubicacion Where CiudadID=" &DropDownList2.SelectedItem.Value, MyConnection3)
MyCommand3.Fill(du,"Ubicacion")

DropDownList3.DataSource = du.Tables("Ubicacion").DefaultView
DropDownList3.DataTextField = "Descripcion"
DropDownList3.DataValueField ="UbicacionID"
DropDownList3.DataBind()


End Sub


Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
If Not IsPostBack

Dim dc As DataSet
Dim MyConnection2 As SqlConnection
Dim MyCommand2 As SqlDataAdapter

dc = New DataSet ()
MyConnection2 = New SqlConnection("SERVER=MDS01; DATABASE=be; INTEGRATED SECURITY=false;PASSWORD=sa;USER=sa")

MyCommand2 = New SqlDataAdapter ("select CiudadID, Nombre_Ciudad from Ciudad Where EstadoID=" &DropDownList1.SelectedItem.Value, MyConnection2)
MyCommand2.Fill(dc,"Ciudad")

DropDownList2.DataSource = dc.Tables("Ciudad").DefaultView
DropDownList2.DataTextField = "Nombre_Ciudad"
DropDownList2.DataValueField ="CiudadID"
DropDownList2.DataBind()
end if
End Sub

Private Sub DropDownList2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
Dim du As DataSet
Dim MyConnection3 As SqlConnection
Dim MyCommand3 As SqlDataAdapter

du = New DataSet ()
MyConnection3 = New SqlConnection("SERVER=MDS01; DATABASE=be; INTEGRATED SECURITY=false;PASSWORD=sa;USER=sa")

MyCommand3 = New SqlDataAdapter("select UbicacionID, Descripcion from Ubicacion Where CiudadID=" &DropDownList2.SelectedItem.Value, MyConnection3)
MyCommand3.Fill(du,"Ubicacion")

DropDownList3.DataSource = du.Tables("Ubicacion").DefaultView
DropDownList3.DataTextField = "Descripcion"
DropDownList3.DataValueField ="UbicacionID"
DropDownList3.DataBind()


End Sub