warning cannot modify header information - headers already sent.

Please help me fix this code mobilechat wml

$status=file('../text/bannames.txt');
for ($ri=0; $ri<count($status); $ri++)
{
$resultban=rtrim($status[$ri]);

if($nimi=="$resultban"){$admin="5";}
}
if($admin=="5"){
header ('Location: ../tools/yourbanned.php');}

$status=file('../text/bootnames.txt');
for ($ri=0; $ri<count($status); $ri++)
{
$resultboot=rtrim($status[$ri]);

if($nimi=="$resultboot"){$admin="6";}
}
if($admin=="6"){
header ('Location: ../tools/yourbooted.php?nimi=$nimi');}
$status=file('../text/bannames.txt');
for ($ri=0; $ri<count($status); $ri++)
{


$resultipban=rtrim($status[$ri]);

if($nimi=="$resultipban"){$admin="8";}
}
if($admin=="8"){
header ('Location: ../tools/yourbanned.php');}