Can't get caption to show up!

var $overlay = $('<div id="overlay"></div>');
var $image = $("<img>");
var $caption = $("<p></p>");

//add image to overlay
$overlay.append($image);
 // caption
$overlay.append($caption);
// Overlay
$("body").append($overlay);

//1Capture the click event on a link to an image
$("#imageGallery a").click(function (event){
 event.preventDefault();
  var imageLocation = $(this).attr("href");
//1.2 Update overlay w/ the image linked in the link

  $image.attr("src", imageLocation);
  //1.1. Show Overlay
  $overlay.show();
});

  //1.3 Get child's alt attribute set as caption
var captionText = $(this).children("img").attr("alt");
$caption.text(captionText);
//when overlay is clicked
  //3.1 hide overlay
$overlay.click(function(){
  $overlay.hide();
});