You must have a correctly formatted card for your operating system in one of the slots. Please insert a suitable memory card into the correct slot and re-insert USB reader.
If the memory card is not formatted correctly, you will need to format the card either in the PC or in your device. CAUTION – Formatting a card will erase all data.
Make sure the memory card is the correct way up and that you are using the correct slot (if using a multi-slot device) – Do NOT use force.
You will also need to check that your memory card is compatible with your USB Reader.
A SDHC/MicroSDHC memory card requires a SDHC/MicroSDHC compatible reader. Many older readers (including ones in PCs) may not be SDHC compatible.
A SDXC memory card requires a SDXC compatible reader and a exFAT compatible operating system. Proceed with caution.