geniva on "[Plugin: BackUpWordPress] Mysqldump: mysql: not found"

I'm getting the same issue for my two websites on 4.4.2, but on another the same everything works fine!
The effect of this error appears very interesting. Scheduled backup is not created, not only for the database, but also for files.
However, when I enter the BackUpWordPress control panel, backup starts immediately without my request. As a result I get mentioned error message, and at the same time the backup is successfully created.