Fatal error: Call to undefined function: imagecreatefromjpeg()

Fatal error: Call to undefined function: imagecreatefromjpeg() in c:\apache\htdocs\houze\testb.php on line 8


Hvorfor siger den nu det ??!

<?
$uploadfile = 'mig.jpg';
$size = 8;
$rotate = 360;
$xstart = 5;
$ystart = 15;
$tekst = "minsite.dk";
$im = imagecreatefromjpeg($uploadfile);
$sort = ImageColorAllocate($im,0,0,0);
$font="HZ.ttf";
ImageTTFText($im,$size,$rotate,$xstart,$ystart,$sort,$font,$tekst);
header("Content-type: image/jpeg");
ImageJPEG($im);
ImageDestroy($im);

?>

jeg prøver bare at få den ene del til at virke.

Tak for hjælpen!