script werkt niet in firefox

$imtype = $_FILES["picture"]["type"];

    if ($imtype == "image/x-png"){
        $extension=".png";
    }
    elseif ($imtype == "image/pjpeg"){
        $extension=".jpg";
    }
    elseif ($imtype == "image/gif"){
        $extension=".gif";
    }
if ($extension != '')

$imtype = $_FILES["picture"]["type"];
 
    if ($imtype == "image/x-png"){
        $extension=".png";
    }
    elseif ($imtype == "image/pjpeg"){
        $extension=".jpg";
    }
    elseif ($imtype == "image/gif"){
        $extension=".gif";
    }
if ($extension != '')

<?php
elseif ($imtype == "image/jpeg"){
       $extension=".jpg";
}
?>

<?php
elseif ($imtype == "image/jpeg"){
       $extension=".jpg";
}
?>