Page Reloading problem

Hi
I am facing the  proplem that on the main page is showing the childe page as Popup.
on the child page popup i have used the button on chick of that i have write the script code by which it's load the main page again.
it's working fine but when main page load it's not going in the
if(!ispostback ){} condition block plz give soluation what i did.
i can't use the Respone.Redirect(). & also Server.Transfer() only i have to use the script for that.
Script which i have wiritten to Reload the main page-:
StringBuilder sb = new StringBuilder();
        sb.Append("<script type='text/javascript' language='javascript'>");
        sb.Append(System.Environment.NewLine);
        sb.Append("window.close();");
        sb ...