"Document is null" with iframes

"Document is null" with iframes


Hello, i am build one webapp, www.pixeldesing.com , now i am work with
"blog" section of the web, when i click on "blog" link, one <iframe>
load one wordpress blog, all found ok, but, into wordpress, i have one
link with jquery function:
Code:
*****************************************
$('.principal').click(function(){
$('#cuerpo', window.top.document).load('../cuerpo.php');
});
*****************************************
This function, load "cuerpo.php" into "cuerpo" id div of window.top,
load html well, but, not found the javascripts, and firebug tell me
one error "document is null"....
Someone can help me?, thanks.