Helpp!!!!!! .. Hi my label isn't changing after i press the button and switch to the other viewController

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var aButton: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        aButton.setTitle("Press me", forState: .Normal)



    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

        if segue.identifier == "showPlaylistDetailS"  {

            let playlistDetailController = segue.destinationViewController as!
            PlaylistDetailViewController

            playlistDetailController.segueLabelText = "yay!,you pressed me"

        }
    }

}

import UIKit

class PlaylistDetailViewController: UIViewController {

    @IBOutlet weak var buttonPressLabel: UILabel!
    var segueLabelText: String = ""
    override func viewDidLoad() {
        super.viewDidLoad()

        buttonPressLabel.text = segueLabelText
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}