logging/writing to a file on Geronimo

I have a EJB application deployed on Geronimo. In my application I want to log
some information to a file. I use logback as my logger. I have configured logback with a
xml file. When I run some test locally in eclipse the logback creates a log on the prosjects root folder(just like i wanted to).

But when I deploy my application to the Geronimo server, no logging is done!
Does someone know what might cause this?
Could there be a security setting? Or do I need to configure logback in a different way?
I appriciate all help and suggestion!