Have you configured your admin.password file? This is located in [istall-dir]/conf/admin.password
It should look something like this:
Also, you can start Wowza in stand alone mode [install-dir]/bin/startup.bat|startup.sh and view the logs in the console. Please post what you see in the console here if you are still having trouble.
# Admin password file (format [username][space][password][space][group]|[group])
#username password group|group
username password admin|advUser