How can i show the profile image in a lightbox?

How can i show the profile image in a lightbox?

I tried this:

$href = $user->getIconURL('large');

$icon = '<a class="elgg-lightbox" href="'.$href.'"><img src="'.$href.'" /></a>'; 

Profile picture gets shown well but when i click on it the lightbox opens, but it doesn't show the picture, instead it shows the file in 'editor' mode.

Here is a example link