Need more info.
I don't know the answer, but it would be helpful if you said which NG website you are referring to and which specific items, and what the problem is about.
On some sites the engines also need a second CDP downloaded that has common files (engine specs and sounds). Even so, I have found that some of these engines (and other items) have errors in TRS2006 because of missing textures and dependencies. In some cases you can find the missing items in other assets by the same author, but it is time consuming hunting for them.
