Ram disk error : FR_NO_FILESYSTEM

[ECrom.1]

Following me prev. question:

I am using STM32F429zi board

But found a RAM_DISK example for 9i board

I ran with / without RTOS

In both cases :

all these word fine (return woth OK :(

FATFS_LinkDriver, f_mount, f_mkfs,

But when I call f_open I get FR_NO_FILESYSTEM

How can that be ?