In my rails 3 app, simple_captcha doesn't display image on production mode

Simple_captcha работает на моем компьютере разработчика, но не работает на моем сервере общего хостинга (Dreamhost).

ImageMagick установлен, и RMagick там в порядке. What could be wrong?

I checked the log and it doesn't show any error message.

Started GET "/simple_captcha/0245065ca02e2f4fadc22b3f08e1357ea74221f8?time=1304535698" for 99.122.173.225 at Wed May 04 12:01:38 -0700 2011

When I type the address(/simple_captcha/0245065ca02e2f4fadc22b3f08e1357ea74221f8?time=1304535698), it says that "the image cannot be displayed because it contains errors".

Any idea what's wrong?

Thanks.

Sam