You must be connected to the Internet (WiFi / 3G / 4G or ethernet) to be able to search for media information.
Make sure that your file is named correctly. If this is not the case, you can do it directly from the ARCHOS video application by pressing next to the video.
For a series, it is customary to use the following nomenclature "Name SxxEyy series" which corresponds to the xx for the season number and yy for the episode number. "Breaking Bad S01E01" for example is episode 1 of the first season of Breaking Bad.