I installed ifolder server on my ubuntu machine with mono 2.0 following exactly this howto: x2b4 How to install iFolder on Ubuntu server

I can access the admin interface and can login with the user I created over the web interface.
When I try to connect with the ifolder client on windows I just get an error saying the connection could not be established.
I looked through various logs in the ifolder and simias directory in AppData but I didn't find any useful information.

Can anybody give me some hints to find the problem?

thanks in advance