In order to receive proper support, your program needs to show it's been registered. Not being properly registered will also cause some program issues as well such as the ability to run built-in routes, among others. People are also less willing to help someone who shows no registered versions because there is a suspicion that the version is pirated. This may not apply to you, but how do we know.
Showing what version(s) of Trainz you are running also helps us help you because we can then target our support to that version. If you have multiple versions registered all you need to tell us is which version you are currently running. The asset problem you have maybe version-specific, but without us knowing that we can't help you.
If you have trouble registering, ensure that you are using the SAME username and password to login into the game as you are here on the forums. This is the same username and password in your My Trainz account.
If you have trouble registering, as you've said, we recommend you contact the helpdesk.