have similar problem but mine is i am using mac with 10.9.3 and i can not communicate with the leonardo at all. tried all mean. they say that the new os made its own driver and overriding the one that comes with the arduino package. 
have similar problem but mine is i am using mac with 10.9.3 and i can not communicate with the leonardo at all. tried all mean. they say that the new os made its own driver and overriding the one that comes with the arduino package.