OS X Gatekeeper occasionally shows this message when it does not recognize an installer's digital signature. To run the application for the first time, you will need to disable Gatekeeper as follows:
- Go to System Preferences... | Security & Privacy | General tab.
- Click the Lock icon in the lower left corner and enter your password to make changes.
- Select Allow apps downloaded from: Anywhere.
You can enable Gatekeeper again after the first successful launch of the application.