"sh: /mogrify: No such file or directory"

This has actually nothing to do with specially with debian lenny. This problem can happen on any machine which runs a apache webserver. In a PHP Script I use a ImageMagick function called mogrify to resize the images automatically. It did not work and in my /var/log/apache2/error.log I found this entry:

"sh: /mogrify: No such file or directory"

The solution was very simple. I had activated PHP SafeMode which prevent PHP Scripts from using the exec command. After I deactivated Safe Mode ImageMagick works how it should.