Recently upgraded from LG Volt 2 to a Galaxy J7 perx (and what does that perx stand for anyway?). So today I removed the 4GB Sandisk microSD card from the LG phone and put it into the Samsung one. I am almost certain that I followed directions properly and put it in the right place, snapped it in. But then turning the J7 on it doesn't acknowledge the presence of this card. Any ideas what the problem is? Thanks in advance.