Master System games not recognised in emulationStation

Hi all,

I made an Emulationstation setup for a few days, for now on my Windows PC to try and later to make a Raspberry Pi console for my nephews. I have 15 consoles that are well recognized with several games in each and they work all. Unless the Master system console that is not recognized, I put some games in the /mastersytem folder but the console does not appear in the list with others. Normally it is emulated with RetroArch, is there something special to do for this console or can you tell me what could be the problem please?

Thank you