NSView fade animation doesn't work

Question

I have created a new project with one button and one hidden NSView (I called this annimationView). The idea is when user pressed the button than the hidden view should fade in and out. But nothing happens on the first time. If I press the button again it works perfectly.

This is my code. Does have anybody an idea what i'm doing wrong?

 override func viewDidLoad() {
    super.viewDidLoad()
    animationView.wantsLayer = true
    animationView.layer?.backgroundColor = NSColor(red: 223/255.0, green: 240/255.0, blue:  216/255.0, alpha: 1.0).CGColor
    // Do any additional setup after loading the view.
}

@IBAction func click(sender: AnyObject) {

    NSAnimationContext.runAnimationGroup({ (context) -> Void in
        self.animationView.hidden = false
        context.duration = 2.0
        self.animationView.animator().alphaValue = 1

        }, completionHandler: { () -> Void in

            self.animationView.alphaValue = 0
            self.animationView.hidden = true         
    })
}