You are probably using a GNU/Linux distribution other than the ones tested. For this you should verify that the content of the file /usr/share/ehorus/.vnc/xstartup launches some command that your GNU/Linux server understands to start a window manager. The most basic is xterm.
Depending on the window manager you will have to add a window manager or another, for example in gnome it can be (depending on the version) gnome-session or others, in short, different types depending on your GNU/Linux distro. If you don’t know it try this file as a starting point:
#!/bin/sh xterm &