TCAD course labs error on Android

I'm going through training examples and I run on Android problem.

If I run this code on iPhone simulator I get the correct value and if I run it on Android I get null value.

L('add')

where 'add' is the key in mine i18n/en/strings.xml

Here is the whole method:

bh.ui.createBountyWindow = function(/*Boolean*/_captured) {
        var win = Titanium.UI.createWindow({
            title : (_captured) ? L('captured') : L('fugitives'),
            activity : {
                onCreateOptionsMenu : function(e) {
                    var menu = e.menu;
                    var m1 = menu.add({
                        title : L('add')
                    });
                    m1.addEventListener('click', function(e) {
                        //open in tab group to get free title bar (android)
                        var tab = (_captured) ? bh.capturedTab : bh.fugitivesTab;
                        tab.open(bh.ui.createAddWindow());
                    });
                }
            }
        });
        win.add(bh.ui.createBountyTableView(_captured));
 
        //if I call here L('add') on iPhone I get the value and on Android I get null
 
        if(Ti.Platform.osname === 'iphone') {
            var b = Titanium.UI.createButton({
                title : L('add'),
                style : Titanium.UI.iPhone.SystemButtonStyle.PLAIN
            });
            b.addEventListener('click', function() {
                //open modal on iOS - looks more appropriate
                bh.ui.createAddWindow().open({
                    modal : true
                });
            });
            win.setRightNavButton(b);
        }
        return win;
    };

The official code is here.

Other strings are OK on both platforms but they are called from different methods but I don's see why that matters. Any ideas?

EDIT:

The problem is somewhere else. This is really strange.

Here is the strings.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<resources>
    <string name="fugitives">Fugitives</string>
    <string name="captured">Captured</string>
    <string name="add">Add</string>
    <string name="capture">Capture</string>
    <string name="delete">Delete</string>
    <string name="busted">Busted!</string>
    <string name="still_at_large">Still At Large</string>
    <string name="new_fugitive">New Fugitive</string>
</resources>

here is the code:

logger.info(L('fugitives'));
logger.info(L('captured'));
logger.info(L('add'));
logger.info(L('capture'));
logger.info(L('delete'));
logger.info(L('busted'));
logger.info(L('still_at_large'));
logger.info(L('new_fugitive'));

here is the output on Android:

I/TiAPI   ( 1625): (kroll$1: app://app.js) [669,2084] Fugitives
I/TiAPI   ( 1625): (kroll$1: app://app.js) [1,2085] Captured
I/TiAPI   ( 1625): (kroll$1: app://app.js) [4,2089] null
I/TiAPI   ( 1625): (kroll$1: app://app.js) [4,2093] null
I/TiAPI   ( 1625): (kroll$1: app://app.js) [2,2095] null
I/TiAPI   ( 1625): (kroll$1: app://app.js) [3,2098] null
I/TiAPI   ( 1625): (kroll$1: app://app.js) [3,2101] null
I/TiAPI   ( 1625): (kroll$1: app://app.js) [2,2103] null

Here is the output on iPhone:

[INFO] Fugitives
 
[INFO] Captured
 
[INFO] Add
 
[INFO] Capture
 
[INFO] Delete
 
[INFO] Busted!
 
[INFO] Still At Large
 
[INFO] New Fugitive

WHAT IS SO DIFFERENT IN THOSE STRINGS ON ANDROID???????????

So the answer is so simple....

Project -> Clean

Now why is that? Could someone explain me what is going on in the background that Clean fixed?