How to crop image in Image_Canvas PHP PEAR package

Question

I can't get it to work it just does nothing. I'm using Image_Canvas PEAR package on shared hosting it works but I can't crop image.

My syntax is:

$Canvas->setClipping(array('x0' => 10, 'y0' => 10, 'x1' => 200, 'y1' => 200));

Any ideas?