The catalog page says that the SD card supports the FAT file system. I had a 16mb SD card which could only be formatted FAT or NTFS (Windows 7 wouldn’t let me format it FAT32 presumably due to the small size). Windows recognized the card, but the Spider refused to mount it, displaying a warning questioning if it is FAT32 or not.
Swapped in a 512MB card (yes, these are both ancient cards) formatted FAT32 and it mounted just fine.
I assume the difference is FAT vs FAT32, although I could format the 512 as FAT to test if this isn’t a known issue.