windows Warning message is coming when trying to Closing Parent window from child window

Question

I have put this code in my child window java script part to Close Parent window from child window

try
{
if(!window.opener.closed)
{


alert(window.opener.location);

window.opener.close();
}
}
catch(err)
{
}



But while clicking the close button , its giving one alert message "the window you are viewing is trying to close . Do you.....?".

I dont want this message.
Can anybody help me in thi.

Thanks in advance