Problems with dialog windows

HI all.
This is the code for creating a simple dialog window,
but when I display this window, it is empty.

Someone can tell me what's wrong ?

thanks

Ivan

var myWin = new Window('window', 'Title', [100,100,400,300]);

myWin.msgPnl = myWin.add ('panel', undefined , 'Available models');

myWin.msgPnl.titolo = myWin.msgPnl.add('statictext', undefined,'Select your model');
myWin.radio_1 = myWin.add('radiobutton',undefined, '2 X 3');
myWin.radio_2 = myWin.add('radiobutton',undefined, '3 X 5');

myWin.radio_1.value = (true);