only some microSD work

hi
i have 10 microSD 8-GigaByte brand BlackPCS for use with mp3 DFplayer mini.

al micro SD are FAT32 and work well on computer and MP3 files.
all microSD are new
all microSD store the same mp3 files
using library DFRobotDFPlayerMini.h

problem is: only 3 microSD work on DFplayer. The rest gives error initiating DFplayer:
Quote

Unable to begin:
1.Please recheck the connection!
2.Please insert the SD card!

i have tried:

FAT32 Reformat the not-working microSD. Even change the allocation unit size
also inspected properties for both working vs not-working and are equal

any help?

Never heard about this brand. Any link?