Is the card fully in, as shown in the pictures here:
http://jevois.org/start/assets/images/microsd-card-insertion.jpg
if you have short fingernails, you may want to push it in using a credit card or such, just beware that if you slip, the microSD will fly out, so be ready to catch it.
every unit is tested twice at the factory, so we have not had many defects, but if you believe you may have a bad camera, please email us at jevoisinc@gmail.com with your order number and we will ship you a replacement unit to try out.