am1808, kernel 3.17, usb detection issue

Dar all,

i succesffully had USB working on kernel 3.17 on a AM1808 based board.

After reboot, with key inserted, automount detect the key and mount it correctly.

Once removed, i see a message as:

[root@test local]# usb 1-1: USB disconnect, device number 2
FAT-fs (sda1): unable to read boot sector to mark fs as dirty

But once the key is re-inserted, i don't see it detected nor mounted.

also lsusb doesn't show the usb pen anymore.

Could i have some issue with udev / automount  or menuconfig ?

Thanks