In attempting to use the DualList control, I've found that I can't get it to populate during an event. If I populate it during the page load, it works fine, but if I do it on say an itemChangeEvent, it won't populate. Can anyone explain why?

 Sub bindDualList()
            Dim objRoles As New Roles.RoleController
            Dim arrSysRoles As New ArrayList
            arrSysRoles = objRoles.GetPortalRoles(PortalId)
            Dim arrAvailableAdminRoles As New ArrayList
            Dim arrAssignedAdminRoles As New ArrayList
            arrAvailableAdminRoles = arrSysRoles
            ctlAdminRoles.Available = arrAvailableAdminRoles
            ctlAdminRoles.Assigned = arrAssignedAdminRoles
            ctlAdminRoles.DataBind()
        End Sub

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            'Put user code to initialize the page here

             If Page.IsPostBack = False Then
                
                bindDualList() 'Works 
            End If
        End Sub

Private Sub ddlLocs1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddlLocs1.SelectedIndexChanged
            'fill dualistcontrol
            bindDualList() 'Doesn't work
  End Sub