whenever i go into properties to edit the rollingstock in trainz(ex: fill a hopper with coal) i'm met with a grey screen with no way of choosing which property i want. i don't know what to do
There is not a great deal of information in that post to be able to give you a clear solution. The most obvious point to consider here is that not all rolling stock was created to carry cargo and therefore cannot be edited.
The following answers would be helpful:
What version of Trainz are you using?
Can you identify the <kuid> code of a rolling stock item that you are trying to edit?
