What do you mean you can't change to a different aircraft? (When? With all aircraft? Just from the F-104? You can't find the button's location? The selection screen isn't appearing?)

I don't know much about the TCE (though I would assume it's pretty much the same as the ACEs), but the fact that it's a program designed to work with FS9 (along with the F-104) is almost certainly the cause.

As a tip, it's generally not a good idea to buy FS9 payware for FSX. You may have had some success in the past with installing FS9 freeware, but payware aircraft are much more complex and it's more than likely that something won't work.

-boeing247   :)