Try another SD card ... borrow one to see if it works.
The slot in this device will accept a card up to MicroSD (64 GB Max).
It might pay to format the card you have first too.
Format SD card
From any Home screen, tap Apps.
Tap Settings.
Scroll to 'System,' then tap Storage.
Under 'SD CARD,' tap Format SD card.
Tap Format SD card again to confirm.
Tap Delete all.