Sorry, I'm having a bit of trouble understanding due to the way you have worded it.
You seem to be saying that you have tried other SD cards in your phone that work fine, but the one you already had does not work. Is it just the one microSD card that does not work in your new phone? It could be a bad card.
Do ANY sd cards work in your phone? If so, then it's not a defective phone. It could be that the sd card was encrypted on the last device used and the phone isn't able to recognize or refusing to recognize it due to DRM issues. Not sure, really. You may have to backup the info on the card to a PC, format it, then restore the information to get it recognized.
Or did you mean that the card works fine in other phones, but not in yours? That's where I'm confused. If this is the case, then there is a possibility that the sd slot in the phone is defective. Make sure other SD cards also don't work if you can before taking it in for repair or replacement under warranty.