The counterfeits can't be told from real SanDisk cards by looking at the packaging - they're counterfeiting that perfectly. As B. Diddy said,
SD Insight will tell you what's in the card. (If the date in some time in 1970, it's counterfeit - 0 is Unix date 1/1/70, and some counterfeiters neglect to put in a reasonable date when they reprogram the card. [There's a whole little computer in that card - controller, firmware and the storage area you use. It can be programmed to say it's any size, so you may have a 512MB card that claims to be 16GB.)
If SDInsight says it's a good card, contact SanDisk at
SanDisk microSD Tech Support (there's live chat at the upper right). Even if the problem is your phone, they'll try to find out what's wrong. They're a great company to work with (which is why I always pay the extra it costs to buy their cards - the service is worth it).