Have you configured StreamNameAlias properly on the new Wowza 4 install? It is not pre-installed. You would also have to add the alias to the StartUpStreams.
What do you see in the access log when you start the stream?
You can also
use .stream files instead of StreamNameAlias. You cannot mix these techniques however. If you use .stream files do not have the StreamNameAlias addon configured in the same application.
If still a problem, can you show the shoutcast url you are using here? If not, open a ticket by writing to
email@example.com. Zip up /conf and /logs folders and include those, and include a link to this thread for reference