Depends where you store the downloads, but goto drive x/trainz/downloads; if you forgot the kuid, look it up on the DLS again, (best to always write down things as you go). I tried to rename all to the actual name of the asset, but this made a mess. Seems as Auran wants only the number with is not so good for the user. Just one more thing they need to clean up before tryin to make a buck from another mistake (new version).
Basically the assets such as locos have separate bogeys and other things that get reused on different models. These are the dependencies, use a tool such as Tafweb's some thing or other. You can tell how long it is since I used TRS2004 can't you. Anyway if you pick up TRS2009 it does all this for you.
Hi as others have mentioned you probably have missing dependencies.
If you know the kuid numbers of the locos you downloaded you can go back to the Download station and locate the files always click and open where it says download page for the loco, if you look at this page at the bottom will be a list of dependencies the loco needs If you have just one file missing you will get the problem you have now.
If you still have problems post back here with the kuid numbers of the locos you have missing content and I will check them out.