Error : object # has no method 'open'

I try to create a button on click to redirect me to another view of a controller from the index file I followed instruction and i read lot of article and i still get the same error

object #<view> has no  method  'open'

function goPlay(e) {  
     var w = Alloy.createController('play').getView();
     w.open();
 
}

<Button id="btnPlay"  class="btn btn-play"  bottom="0">play</Button>

Note i use alloy framework on windows 7 platform using android emulator

Please help