Someone at my company had the issue where this happened:
[RoutePrefix("R2D2")]
public class R2D2RobotController {...}
Valid Route (200 Success):
api/R2D2Robot
Invalid Route (404 error):
api/R2D2
As far as I was aware the [RoutePrefix] was an valid attribute to use. I'm not sure what is causing it, but my thoughts are that there is a confugration option that either builds the url from the controller name, or from the [Route] attribute