transition not working in io7

Hello

I updated to 3.2.0 today, i' m testing my app, and i have a problem with transition, my code

var win1 = Titanium.UI.createWindow({
                    url:'xxx.js'
                });
            win1.open({transition:Titanium.UI.iPhone.AnimationStyle.FLIP_FROM_LEFT});

Thk so much.