How to fix 404 Error in Flex

When i click the button it should be open the popup So i defined the javascript as below

function open_manifestInfo(url, target, type) { window.open(url, target, type); }

At first time click the button, popup is working normally But next time click the button, 404 error is displayed So i have refreshed the popup it's same If i copy the url at new open the browser then it is working normally

Therefore i want to open new browser and then execute popup How can i do that??? Thanks