F u followed the steps exactly then it should work as i do it countless times lol but start from the beginnin, uve created a dyndns account and set it up in Inadyn and its successfully connected.
What router do you have? Have u forwarded your http port in your router to the right IP Address of the box? If your trying it via 3g you need to put the port number at the end too, so http://xxxx.dyndns.tv:80