Imagick sepiaToneImage doesn't work without reason.

[sabater_wb]

I don't know what is wrong. When I run the following php script I get an light blue image.

<?
$im = new Imagick("photo.jpg");
$im->sepiaToneImage(80);
$im->writeImage("photo.jpg");
$im->destroy();
?>

---
Server configuration:
magickwand 1.0.8
ImageMagick 6.5.4-7 2009-08-12 Q8 http://www.imagemagick.org
Imagick Module: 2.3.0

[varghese]

may i know that input value is constant(80)?