trying to put roms on r4 cart but keep getting error

error sayscouldn't find _DS_MENU.DAT ive tried a million times but its doing the same thing ive done loadsa these carts what am i doing wrong please help me thanks a lot

Reinstall your firmware. You got rid of the _DS_MENU.DAT file that is needed to run the R4. Remember to put the firmware files (like the above mentioned) in the root of the drive.