void UCTariffSelectPicker_Loaded(object sender, RoutedEventArgs e)
{
serviceFacade = new TariffFacade(CPApplication.Current.CurrentPage);
this.DataContext = queryfilter;
Loaded -= UCTariffSelectPicker_Loaded;
}
void UCTariffPicker_Loaded(object sender, RoutedEventArgs e)
{
this.Loaded -= UCTariffPicker_Loaded;
tariffFacade = new TariffFacade(CPApplication.Current.CurrentPage);
InitializeCategoryComboBox();
}