MacBook not recognizing miniSD card

I wanted to download a few songs onto my Samsung Upstage cell phone, so I took the miniSD card out of the phone, into the adapter, and put that into my memory card reader. The light showed up (meaning the memory card reader read the memory card), however, nothing showed up on my Mac saying that it was there. So, I tried putting the miniSD card into my phone, and plugging my phone on the other end of the USB. My phone recognized the command that I was trying to connect it to another source, however, my computer did not. This wasn't a problem on my old Gateway laptop. I don't think I'm doing anything wrong.. but do Macs usually reject miniSD cards? (my regular sized SD cards work perfectly fine, if that's any help)