PSX Bios not recognized

[amdultra]

Hey all!
I am getting crazy about this. I read tons of articles about this topic and watched videos.

May Bios folder is filled with the right Bios, right name (case sesitive..i know), right md5. But the Bios tool in emulationstation still does not recognize the bios files.

I have installed the latest version of recalbox on my usb stick, everything else works fine.
I also did a factory reset of recalbox with no success. Does anyone have a idea what else i could check? Thanks!