Textarea blur does not work in modal windows?

I have the following code where I create a simple modal window with a textArea. When I click on the screen outside the textArea I want that the keyboard hides. Does anyone have a hint why this does not work?

//file1.js calls the modal window 
var modalWindow = Ti.UI.createWindow({
});
var req   = require('ui/common/services/messagesSendView');
var messagesSendView = new req();
 
var navGroup = Ti.UI.iPhone.createNavigationGroup({
    window : messagesSendView
});
messagesSendView.navGroup = navGroup;       
modalWindow.add(navGroup);
 
modalWindow.open({
    modal: true,
    modalTransitionStyle: Ti.UI.iPhone.MODAL_TRANSITION_STYLE_COVER_VERTICAL,
    modalStyle: Ti.UI.iPhone.MODAL_PRESENTATION_FORMSHEET,
    navBarHidden: true
});

//messagesSendView.js: modal window code
function messagesSendView(){
    var self = Ti.UI.createWindow({
        title:  'Send Message',
    });
 
    self.addEventListener("click", function(e){
        Ti.API.info("clicked"); //this is called when I click
        textArea.blur(); // this should clear the keyboard
    });
 
    var textArea = Ti.UI.createTextArea({
      top: 15,
      width: Ti.UI.FILL, height : 140, left: 20, right: 20
    });    
 
    self.add(textArea);
 
   return self; 
};
module.exports = messagesSendView;