java - Press [enter] to start the game, no error -

i trying function where, when press enter, start game, isn't working. there no error. have followed tutorial.

here code:

import greenfoot.*;  /**  * write description of class menu here.  *   * @author (your name)   * @version (a version number or date)  */ public class menu extends world {      /**      * constructor objects of class menu.      *       */     public menu()     {             // create new world 600x400 cells cell size of 1x1 pixels.         super(800, 500, 1);           prepare();     }       public void start()     {         {             if(greenfoot.iskeydown("enter"))             {                 minionworld minionworld= new minionworld();                 greenfoot.setworld(minionworld);             }         }     }      /**      * prepare world start of program. is: create initial      * objects , add them world.      */     private void prepare()     {         controls controls = new controls();         addobject(controls, 300, 100);         controls.setlocation(175, 50);     } } 

if(greenfoot.iskeydown("enter")) 

change line

if(greenfoot.iskeydown("enter")) 

key name enter "enter" small-caps.