I am using Page.IsPostback to load the first ddl. But I am not using IsInAsynchPostBack. I've never used it, I'm not sure how to use it.
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (Not Page.IsPostBack) Then
Common.BindCruiseLine(cbCL)
End If
End Sub