To create a backup of my design projects getting error

Hi guys,
I have tried to create a backup of my design projects which include Photoshop files, in design files and Illustrator logos. At the time of backup, none of these programs is running but I get an error when ejecting the backup disk. I am running Mac OS X. Any ideas?

The disk “Backup” couldn’t be ejected because “Photoshop” is using it.
Quit that application and try to eject the disk again.
