SD memory cards
Has another SD Card worked? is this the first you card you tried?
Be sure you have the correct type (size) SD card, there a couple of SD card types, micro (very small, etc.). It should go in only one way, does it fit and install easily? It should SNAP into placye.
A SD card is supposed to ONLY GO IN ONE WAY, the correct way.
It should SNAP in. Try to insert it in a different way very carfully.