Is your action not firing after Gesturizer recognizes your gesture?
If your action is an Activator action, then that specific action is not compatible with the current mode you are in. For example, you can not activate Graviboard while in an application.
If your action is a URL, then that URL is probably invalid.
This is especially pertinent on the lockscreen, as URLs and many activator actions cannot be activated from the lockscreen.
You can only launch an application using Activator from the lockscreen if you have no passcode set.