By default, for whatever reason, some phones do not ship with TTS (Text to Speech).
Once you install that feature on your phone, Enhanced SMS & Caller ID+ will work flawlessly for you!
Perhaps the following link will help: https://play.google.com/store/apps/details?id=com.google.tts
If you are sure that you have TTS data already installed, sometimes rebooting your phone will get things working properly!