Vanilla 2

I've got code for pretty photo like this:

$(document).ready(function(){
$("a[rel^='prettyPhoto']").prettyPhoto({theme:'facebook'});
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(function(){
$("a[rel^='prettyPhoto']").prettyPhoto({theme:'facebook'});
});
});

Bind pretty photo after async postback cause an error like this:

Message: '$ppt' is empty or isn't an object
Row: 55
Char: 418
Code: 0
URI: http://localhost/xxx/Scripts/jquery.prettyPhoto.min.js

Any help for me?