I have a new 500 GB Passport Studio that I am using with a MacBook Pro. I am only backing up pictures on it. The initial backup went well, but since then I have added about 150 new images to iphoto and My Passport doesn’t seem to have backed them up. The number of free GB has stayed the same for over 24 hours. The LED light is blinkng, and the Data Gauges are showing zero. Is something wrong?