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.