Iframe get content height/width

Iframe get content height/width

Hy, i have a small question .... Lets say i have a html web page with the folowing code inside:
 
<html>
....
 
<iframe id="myFrame" src=" http://www,google.ro">
 
.....
 
 
The question is how do i get the iframe contents height/width  ?
 
I've found someting like :
 
myIFrame.contentWindow.document.body.scrollHeight
 
But doesn't work ! ....   I have IE9 on WIN7