APEX

I have a print page that I want to open in a new window when the print button is pressed.
I used the example

javascript:window.open('http://www.oracle.com','_blank','toolbar=1,location=1,directories=1,status=1,menubar=1,scrollbars=1,resizable=1,width=630,height=450');

as posted by Roel on November 18th.

Actually my code looks like

javascript:window.open('f?p=&APP_ID.:50.:&APP_SESSION.::::P50_REQ_ID:&P18_REQ_ID.:','_blank','toolbar=1,location=1,directories=1,status=1,menubar=1,scrollbars=1,resizable=1,width=1500,height=900');

The window opens, but the current page goes to a blank page and all it has on it is the word Object. When the new window is close, I use the back button
to go back to the original page I was sitting on. It probably has something to do with _blank, but what do I replace it with?