Permission denied to access property 'href'

I try to reload parent web page from iframe. Here is my code:

<script>$(document).ready(function() {  window.parent.location.href = window.parent.location.href;      });</script>

But it doesn´t work. Firebug says: Permission denied to access property 'href'

I´m on same domain so what´s the problem? I try to do it in Wordpress theme.