Setting a font with GD?

[phpcode]

<?php
header ("Content-type: image/Gif");
$back = imagecreatefromgif ("back.gif");
$textcolor = ImageColorAllocate ($back, 10, 10, 10);

$font  =  "arial.tff"; 

$time = $date = date("H:i");

ImageString ($back, 10, 150, 100, "Last Refresh at: $time", $textcolor, $font);

ImageGif ($back);
ImageDestroy ($back);
?>

 

I'm trying set a font but when I view it I get the error "The image at img.php cannot be displayed because it contains errors" Can anyone see anything wrong with the code?

[Barand]

if you are using ttf fonts, use

 

imagettftext()