That error actually indicates that the applet is running correctly because that is the error the applet shows when it is unable to connect to an iCamSource that the Broker Server told it about, meaning that the applet was already able to talk to the Server.
If this is on a computer that works fine in Vista, then the problem is caused by some sort of firewall or network filtering program running on Linux. Please disable any firewall software temporarily to see if iCamWeb starts working. If it does, we can configure the firewall to work with iCamWeb.