When connecting a computer to a projector whether it be an interactive projector or an LCD a few items to bear in mind:
- Connect the machine to the projector.
- Power the projector on.
- On the Mac go to System Preferences>Display.
- Ensure show mirror options is enabled.
- Go to Arrangement.
- Ensure the displays are mounted on one another.
- Check to ensure resolution is set to automatically optimize for the device.
- If no automatic option is available you can try different resolutions and see which is best (do this after focusing the projector unit).