UIAlertViewDelegate crashes

Hello,

I'm quite new to Xamarin.iOS and I'm trying to display an UIAlertView with 3 buttons and write something in the debugger when one of these three buttons is clicked.

I did that :

public partial class HomeScreen : UIViewController
{
    public HomeScreen () : base ("HomeScreen", null)
    {
    }

    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();

        this.btn.TouchUpInside += (sender, e) => 
        {
            using (UIAlertView view = new UIAlertView("Alert", "Click a button", new HomeScreenAlertDelegate(), "OK", "Réessayer", "Annuler"))
            {
                view.Show();
            }
        };
    }
}

public class HomeScreenAlertDelegate : UIAlertViewDelegate
{
    public override void Clicked (UIAlertView alertview, int buttonIndex)
    {
        Console.WriteLine (buttonIndex.ToString());
    }
}

When I click on my button, it displays the alert correctly but when I click on a button, the application crashes. Not all the time. Indeed, sometimes (very rarely), it works correctly but most of the time, I got this error :

MonoTouch.Foundation.MonoTouchException: Objective-C exception thrown. Name: NSInvalidArgumentException Reason: -[__NSSetM alertView:clickedButtonAtIndex:]: unrecognized selector sent to instance 0xc032b70 at at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication:UIApplicationMain (int,string[],intptr,intptr) at MonoTouch.UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0004c] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:38 at Test.Application.Main (System.String[] args) [0x00000] in /Users/sebastiensougnez/Desktop/Test/Test/Main.cs:16

Is there an error in how I create/use the delegate ?

Thanks