hi .. i am new to dw and using version 6

i am trying to insert some data by using "record insert form" from application objects

the data is saving in mysql database but it doesnot redirect to the other page and the error is

Error Message >>> Warning: Cannot modify header information - headers already sent by (output started at c:\inetpub\wwwroot\heli\TMPjf8da6j3hz.php:2) in c:\inetpub\wwwroot\heli\TMPjf8da6j3hz.php on line 56

and my code near to line 56 is

$insertGoTo = "Knet.php";
if (isset($HTTP_SERVER_VARS['QUERY_STRING'])) {
$insertGoTo .= (strpos($insertGoTo, '?')) ? "&" : "?";
$insertGoTo .= $HTTP_SERVER_VARS['QUERY_STRING'];
}
header(sprintf("Location: %s", $insertGoTo)); // this is line 56
}

Thanks in Advanced