This might help:
What exactly does this mean?
a) it didn't appear in the game visibly when I built it
b) it didn't appear in the shipyard to be built
c) it didn't appear in the map editor screen
d) it didn't appear because it had a cloaking device
e) it didn't appear because the game crashed
The more specific you are in what you DID, the more specific we can be in helping you fix it.
Check these three things:
1) The first line of most .ODFs is what's called the #include script. Your #include should refer to an existing .ODF somewhere in the "ships" directory.
2) Techtrees. Check to make sure the .ODF names correspond to the entries in the techtree.
3) Make sure you actually input the ship's build entry into the shipyard. And check that the "buildItem##" numbers are sequenced properly. I have included two "buildItem8"s or something like that so frequently in my time. It's my most likely error to make. I always check that first. But that's me.
Try that. Then tell us where things fell apart if you can fix it.