please help me, whi replace not work. Thanks. If i write line with replace out from function it is work, but inside function not work... i dont know why, because alerts work well.... It is a script for replace footage by our choice from dropdown menu.

//show window
var mainWindow = new Window("palette", "", undefined);
mainWindow.orientation = "column";

var iconName = ["Bourky_s_destem.mov", "Bourky.mov", "Dest_se_snehem.mov", "Jasno.mov", "Mlhy.mov", "Mrholeni.mov", "Mrznouci_dest.mov", "Oblacno.mov", "Prehanky_dest_se_snehem.mov", "Prehanky.mov", "Skorojasno.mov", "Snehove_prehanky.mov", "Snezeni.mov", "Trvali_dest.mov", "Zatazeno.mov"];

var groupOne = mainWindow.add("group", undefined, "groupOne");

//show dropdown menu

var PH_lisabon = groupOne.add("dropdownlist", undefined, iconName);
PH_lisabon.size = [200, 25];
PH_lisabon.selection = 0;


var PH_berlin = groupOne.add("dropdownlist", undefined, iconName);
PH_berlin.size = [200, 25];
PH_berlin.selection = 0;


var PH_nice = groupOne.add("dropdownlist", undefined, iconName);
PH_nice.size = [200, 25];
PH_nice.selection = 0;

var groupTwo = mainWindow.add("group", undefined, "groupOne");
var applyButton = groupTwo.add("button", undefined, "Apply");

mainWindow.center();
mainWindow.show(); 


// this is work - app.project.item(1).replace(new File(['./ikony/' + PH_berlin.selection.text]));


//click on apply button
applyButton.onClick = function() {
    findAndReplaceIcons(PH_berlin.selection.text, "PH_berlin.mov");
    
}

// replace footage
function findAndReplaceIcons(iconOnLocation, placeHolderName) {

for (var i = 1; i <= app.project.numItems; i ++) {
    if ((app.project.item(i) instanceof FootageItem) && (app.project.item(i).name === placeHolderName)) {
    
alert(iconOnLocation);
alert(placeHolderName);
alert(app.project.item(i).name);
        app.project.item(i).replace(new File(['./ikony/' + iconOnLocation]));
        
        break;
      
      
    }
    
}

}