closing a PDF doc with javascript

Hello. I have a question regarding closing a window that has been programatically populated with a PDF document via javaScript.
 
Example:
I have some code that opens a popup window and populates it with a pdf document...
 
var popupWin = window.open("url/doc.pdf", "popup", "width=600,height=400");
 
Then, somewhere else in the code I am trying to close the window with:
 
popupWin.close();
 
The close method call does not actually close the window. If I look at the closed attribute of the popupWin object it returns true. So, the browser thinks the window is closed but it is not.
 
This code all works fine if I load an HTML page into the popup window but fails when I load a PDF document into the window.
 
Any help would be appreciated.
 
Thanks,
Chris Mizelle
[link=mailto:chrismizelle [at] cox [dot] net]chrismizelle [at] cox [dot] net[/link]