palette don't work on Illustrator

Hello, hello,

I am learing Script UI and Scripting and I have a problem with palette in scripting Illustrator.

I want use palette to make window Script UI and use it to work with layers in illustrator but don't work.

I paste my code :

--------------------------------------------------

var windowString = 'palette\

{text: "My window",\

    myEditText: EditText {characters: 20},\

    myButton: Button {text: "Modify ?"}\

}';

var myWindow = new Window(windowString);

function modify()

{

    var myValue;

    valeur = myWindow.myEditText.text;

    myLayer.name = myValue

};

myWindow.myButton.addEventListener("click", modify);

var myDoc = app.activeDocument;

var myLayer = myDoc.activeLayer;

myWindow.show()

--------------------------------------------------

With type : palette, I can't work with Illustrator object (just app, for exemple app.beep() work) but no with document object or path item.

It's work with type : dialog (I can wotk with path item an othes Illustrator objects) )but I need use palette.

Can I get your help please ?

Sorry for my bad english, i can explain again if you want.