Unidentified Developer error
"eViewer" can't be opened because it is from an unidentified developer. Your security preferences allow installation of only apps from the App Store and identified developers"
Solution: Click the Open button in the warning dialog that appears. To change this permanently go to System Preferences > Security & Privacy. On the General Tab click the little lock in the lower left corner to unlock the general preference pane. Then select the Anywhere radio button beneath Allow applications downloaded from.
Here is another way of saying the same thing:
Apple has now changed the default settings to only download application from Mac App Store and identified developers. you need to change the settings ... System Preferences > Security & Privacy > General > Allow applications downloaded from ... Select "open" to override and install/open the application.