Image creation via PHP

Hi, I  have recently been working on a script which will create an image via PHP, but seems to have stumbled upon a big error.

My script is..

<?

if($ploc=="Hev") { $im = imagecreatefrompng('Hev.png'); }
else if($ploc=="Sky") { $im = imagecreatefrompng('Sky.png'); }
else if($ploc=="Sur") { $im = imagecreatefrompng('Sur.png'); }
else if($ploc=="Dun") { $im = imagecreatefrompng('Dun.png'); }
else if($ploc=="Hel") { $im = imagecreatefrompng('Hel.png'); }

      $kdc=0;
      $kds=0;

      ?>
            <script language="JavaScript" type="text/javascript">
                  function loc(x,y) { s_Loc.innerHTML="Location: "+x+","+y; }
                  function ut() { s_Loc.innerHTML="<br>"; }
                  function kd(kdnum) { s_KD.innerHTML=kdnum; }
                  function kds(kdnum) { s_KDS.innerHTML=kdnum; }
            </script>
      <?

      echo "Number of kingdoms: <span id=s_KD>".$kdc."</span> || Kingdoms Checked: <span id=s_KDS>".$kds."</span><p><span id=s_Pic>Old :: <br><img src=result.jpeg></span><p>";

$width=300;
$height=300;

$image=imagecreate($width,$height);
$bg=imagecolorallocate($image, 0x00,0x00,0x00);

for ($i=0;$i<300;$i++){
      for ($j=0;$j<300;$j++){
            $start_x = $j;
            $start_y = $i;
            $color=imagecolorat($im, $start_x, $start_y);
            if($color==$colour) {
                  $kdc++;
                  imagesetpixel($image,$start_x,$start_y,$color);
            }
            $kds++;
      }
      echo "<script>kds(\"".number_format($kds)."\");</script>";
      echo "<script>kd(\"".number_format($kdc)."\");</script>";
}

imagejpeg($image,"result.jpeg");
imagedestroy($image);

echo "<p>New :: <br><img src=result.jpeg>";

?>

The imagesetpixel() seems to not be working at all and therefore it prints a fully black image. This shouldn't happen. Can anyone suggest a fix? (based on the above script). Quickest and most efficient answer gets..... ooooohh.... 75 points?

EDIT: Upped to 100