Create a Booting Device IRC5

Hi,
I am trying to create a new booting device on a USB Key with RobotStudioOnline v.5.10.0149.
With the system builder, I create a booting device on a USB drive. When a to an X-Start, I choose to install a new system from the USB. I put the USB in the front slot and I try to boot from it I have an error telling me that the USB is unusable… do you have any clue how to fix it?

Thanks you

Moved to RW forum.

I find out that the IRC5 Controller need to have a boot media in FAT32…weird.