window.location is not working

i have problem with navigating to a new page from AJAX.
here a simple function which gives the alert msg but do not move to a new page:

function select_copyEntity(briefcaseQString, field)
{
var newURL = "";
newURL = "to_copy.php?" + briefcaseQString;
alert (newURL);
window.location = newURL ;
}

in beginning for login form, window.location worked correctly. can anyone help me?