I am trying to write an if/and statement based on two different drop down lists. Is it possible to write something with the logic below? The if && statement does not work properly, but will work just fine with a single if statement. I understand the is a bit of code, but this is the only way I can show exactly what is happening.

    function doGet(e) {

  var app = UiApp.createApplication();



  var containerSizeList = app.createListBox().setId('containerSizeList').setName('containerSizeList');

  containerSizeList.addItem(20ft Long);

  containerSizeList.addItem(40ft Long);



  var loadingStyleList = app.createListBox().setId('loadingStyleList').setName('loadingStyleList');

  loadingStyleList.addItem(On Pallets);

  loadingStyleList.addItem(Floor Loaded);



    var tenPalletPanel = app.createHorizontalPanel().setId('tenPalletPanel').setVisible(true);

    var tenPalletLabel = app.createLabel('10 Pallets Available').setId('tenPalletLabel');

    var twentyPalletPanel = app.createHorizontalPanel().setId('twentyPalletPanel').setVisible(false);

    var twentyPalletLabel = app.createLabel('20 Pallets Available').setId('twentyPalletLabel');

    var loadingNotePanel = app.createHorizontalPanel().setId('loadingNotePanel').setVisible(false);

    var loadingNoteLabel = app.createLabel('Note: Only certain products may be floor loaded')

    .setId('loadingNoteLabel');



    var containerGrid = app.createGrid(1, 2);

    containerGrid.setWidget(0, 0, containerSizeList);

    containerGrid.setWidget(0, 1, loadingStyleList);



    var handlerJ = app.createServerClickHandler('palletChangeMe'); 

    containerSizeList.addChangeHandler(handlerJ);

    loadingStyleList.addChangeHandler(handlerJ);

    handlerJ.addCallbackElement(containerGrid);       



  app.add(containerGrid);

  app.add(tenPalletPanel);

  tenPalletPanel.add(tenPalletLabel);

  app.add(twentyPalletPanel);

  twentyPalletPanel.add(twentyPalletLabel);

  app.add(loadingNotePanel);

  loadingNotePanel.add(loadingNoteLabel);



  return app;

}



function palletChangeMe(e){

  var app = UiApp.getActiveApplication();



  if (e.parameter.containerSizeList == 40ft Long && e.parameter.loadingStyleList == On Pallets){

    app.getElementById('tenPalletPanel').setVisible(false);

    app.getElementById('twentyPalletPanel').setVisible(true);

    app.getElementById('loadingNotePanel').setVisible(false);

}



  return app;

}