Verizon Samsung Galaxy Droid phone SD card not being read when plugging into MacBook?

I'm having problems when plugging my Verizon Samsung Galaxy into a MacBook Pro. I keep getting an error message that says the card can not be read. I've plugged it in many times before and it has worked without any issues. I've tried restarting both devices and erasing and reformatting the card with the phone. I also tried erasing the card through the MacBook but was also unable to do so. When I plug the phone into a PC it seems to read the card without any issues as before. Anyone know what the problem might be or how to solve it? Thanks!