Weird problem

[Dementor]

I'm fairly new to ps3 media server but i'm getting the hang of it.
I have a odd problem/bug. When I add a movie (video_TS) folder in the ps3 media server (its the star trek enterprise series) i see only 3 episodes on that part of the dvd, but when I playing it on my pc I see 4 episodes. Is this a bug or what am i doing wrong? It's only with a few dvd's. other dvds of the serie show up as it has to be.
Sorry for my english if it is a bit chubby to read, i'm not very good at english.
I hope someone can help me