IIS \ Apache and header(location: errors

I am trying to execute the following redirection on a web page if the error condition is true if ($_POST["txtPassword"] == "" ) { header ("Location : http://".$_SERVER["HTTP_HOST"].dirname($_SERVER["PHP_SELF"])."/"."errors.php ?Err=".URLEncode("LogOn -002")."&SrcLocn=".URLEncode("LogOn.php")."&Info=".U RLEncode("The Password Cannot Be Empty")."&RtnTo=".URLEncode("LogOn.php")."&Params=".URLEncode($Params)); exit; } The text resolves to http://localhost/public/errors.php?Err=LogOn+-+002&SrcLocn=LogOn.php&Info=Th e+Password+Cannot+Be+Empty&RtnTo=LogOn.php&Params= which is correct. I am running on XP SP1 My problem is that this works fine on IIS 5.0 but fails on Apache 1.3.26 and Apache 2.0.39 No errors are logged in php, apache or event logs. I just get a blank page, viewing this source it is the index.php page (the frameset definitions) Ideas ? Any help appreciated. Thanks