Indesign progress bar doesn't show value

Hi, guys!

I am trying to create a script that is searching for some images in over 100 fodlers. Since it takes much time to complete it, it would be nice the user to have a progress bar. I read the documentation for indesign scripting and also searched for some pregress bar scripting examples over the web, but it still seems I am doing somethig wrong - my progress bar does not show value.

I tried to:

alert the value of the progress bar, just to see if it is changeing - it does;

tried to hide/show the progress bar, hoping that it will refresh and will change it's value - still doesn't;

tried to use window.update() method - still nothing;

I even set a value bigger than 0 in the beginning just to see if is shows something, but it stil doesn't work...

Can some more experienced than me (I am relatively new to scripting) have a look at the code and maybe point out my mistake?

    var ArchCats = ArchFolder.getFiles()

    var ProgBarWin = new Window("window","Progress",[0,0,500,150])
    ProgBarWin.CatProgText = ProgBarWin.add("statictext",[50,20,450,40],"")
    ProgBarWin.ProgText = ProgBarWin.add("statictext",[50,60,450,80],"")
    ProgBarWin.progBar = ProgBarWin.add("progressbar",[50,100,450,130],0,ArchCats.length)

    ProgBarWin.center()
    ProgBarWin.show()

    for (j=0;j<ArchCats.length;j++) {
        ProgBarWin.CatProgText.text = "Searching cat "+j+" out of "+ArchCats.length
        ProgBarWin.progBar.value = j+1

        var ArchCat = ArchCats[j]
        if (ArchCat instanceof Folder) {
            var _sentFolders = ArchCat.getFiles("_sent")
            if (_sentFolders.length<1){
                alert("There is no _sent folder in catalog "+ArchCat.name+" It will not be processed")
                continue;
            }
            else {
                var ArchPages = _sentFolders[0].getFiles()
                for (arp = 0;arp<ArchPages.length;arp++) {
                    ProgBarWin.ProgText.text = "Searching page "+arp+" out of "+ArchPages.length
                    DefineFoldersAndSearch(ArchPages[arp])
                }
            }
        }
    }

Thanks in advance,

Denis.