This will happen with Mac OS 10.8 +. Go to the Security and Privacy section and make sure that „Allow applications downloaded from:“ is set to „Anywhere.“ Alternately, you can approve just Mimio to be able to be installed. All you should need to do is ctrl+click or right-click on the install file and select „open“ from the contextual menu. This time, you’ll see a different pop-up instead of a message saying the app can’t be opened at all. Click „Open“ and you should be all set.