Order email notification: PDF attachment is not attached

[biletnikov]

Hello all,
I configure the order notification(confirmation) by email and intend to use the PDF version of the order in the attachment.

I open Product Store email settings and create an email notification:
Body Screen Location: directs to my order screen and it works fine.
The Attachment Screen Location (XSL-FO): component://order/widget/ordermgr/OrderPrintScreens.xml#OrderPDF
Subject is ok

So, I create an order and send the order confirmation by using the button on the order view screen, I expect to receive the email with the body from (Body Screen Location: ) and the attachment (The Attachment Screen Location (XSL-FO)) , however the body is fine, but the attachment is empty(no files in the attachment)!
No error messages on the screen and in the log file.

Why? What's wrong?
Thanks.