Cuando hago un selectindexchange crea nueva pagina

[charlytesis]

Si tiene ispostback....

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not (Page.IsPostBack) Then
Call CargarCombo1()
Call CargarCombo2()
Call CargarCombo3()
Call CargarCombo4()
End If
End Sub

Private Sub combo1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles combo1.SelectedIndexChanged

With Me.combo2
.DataSource = DS.Tables("tabla1")
.DataTextField = "nombre"
.DataValueField = "codigo"
End With

Me.combo2.DataBind()

If Me.combo2.SelectedItem.Text = ("codigo") Then
combo2_SelectedIndexChanged(Me, Nothing)
End If

End Sub

y asi para los otros combos.........

y el combo esta con Autopostback=true