I recently bought a 4GB micro SDHC card for my nook, as my memory was 99% full and getting a little slow. I went to Barnes and Noble and had them put the card in because I have had issues with getting the back off. They placed the card and told me I had to plug my nook in at home for nook to recognize it. I have plugged it in, turned it off and then turned it back on, and still the SD card says "not installed". How do I install the card?