Are your new classes referenced from the old code? Mxmlc employs a questionable form of "as-needed" linking, so classes that are not referenced from the main application are not even compiled. This referencing requirement is recursive; that is, any classes that are to be included have to be referenced from the main application, or from classes referenced by the main application, or from classes referenced by classes referenced by the main application, and so on. But if your new classes are not referenced at all from the old code, they will be ignored.
First of all, you solved my problem.
The new as class is referenced by another new MXML component, but this new MXML component is not refeenced from application yet.
Thanks a lot.
Forgot to mark it answered.