Sorry, I cam home late this day, so I couldn't do the screenshots for you. But now I did.Can you upload a screenshot from the error message? In Console.app, can u see any lines with SystemVersion faker loaded?
Console:
May 28 23:56:49 myname-ibook-g4 arch: SystemVersion faker for Dropbox Loaded (c) Czo 2015.
The Screenshots are in order of appearance of the steps.
1. see-through icon on Desktop
2. visible icon after dropping it on the apps folder
3. password log in window
4. error message
(when I click on the help button I get here https://www.dropbox.com/help/72