Casio Casiotone CT-S400 User Manual page 176

Display Name
Version Not The USB flash drive file version is not
Supported supported by the Digital Keyboard.
Unformatted The USB flash drive format is not
compatible with the Digital Keyboard.
The USB flash drive is corrupted.
Cause
EN-175
Action
Use a version that is supported by the
Digital Keyboard.
Use a computer to format the USB flash
drive to a format that is compatible with
the Digital Keyboard
Use a different USB flash drive.
Reference