I keep my iPhoto library on a NAS (1 of 2) to free up my internal HDD. I am trying to sync this iPhoto library to my backup iPhoto library on NAS (2 of 2) that I previously did a manual backup on. I recently downloaded FreeFileSync and tried to sync (mirror) my iPhoto library on NAS (1 of 2) to my backup iPhoto library on NAS (2 of 2), but the iPhoto library is greyed out. How can I sync (mirror) the two? Thanks, in advance. Z.