Yes, and I am too.
What version are you attempting this in?
We don't know.
Your registration does not show on the forums, which is important for us to know for this reason.
Are you attempting this in TRS2006, TRS2009? This option may not work in those versions. Maybe not in TS2010 either. Knowing which version would save you and us much time in sorting out your problem. Keep in mind that many things have been added over the years, subtle things, and other things changed so what works now will not work in other versions because it was never thought of and included in the code. Not related to this issue on hand here regarding your cab issue, but very much related. There are many assets that have been updated over the years which now handle alpha-channels. Alpha channels were never operational in early versions so back-dating some assets actually fails on the textures because of this. The same goes for adding new features that are in TS12 and up but never were in previous versions. This maybe one of them.
Again know which version your are up against would have sorted out this problem very quickly.
In order to fix your registration from not showing, contact the helpdesk. They will sort that out for you. Given that it's 2:00 AM in Melbourne right now, you won't hear anything today anyway, besides it takes a couple of days perhaps, but I do more than recommend you do contact them and save your self and us from wasting time on something that may not be valid for your particular Trainz version installed.