Hello! I am trying to get SD communication working on my Teensy++ 2.0 using teensyduino but am having some issues. I had it running fine on an Arduino Pro Micro with Arduino's SD library but that didn't seem to work and now I switched to the SdFat library mentioned on the PJRC website but that still isn't working. I'm running SdFat's default ReadWrite example. The file "test.txt" seems to be created no problem on the SD card but none of the strings are actually getting written with myFile.println("testing 1, 2, 3.") so every time I plug the SD card back into my Mac it just has an empty "test.txt" file. Has anyone had this issue before?

Here's my connections:

VCC -> 3.3V
GND -> GND
CS -> Teensy pin 20
DI -> Teensy pin 22 (MOSI)
SCK -> Teensy pin 21 (SCLK)
DO -> Teensy pin 23 (MISO)

The SD adapter is a cheap one bought from eBay but like I said I had it working on an Arduino so I'm guessing that's not the issue. The SD card itself is a 16gb PNY "Prime Performance" which I have tried formatting a handful of ways. Currently I just have it formatted to FAT32 using mac's disk utility. Thanks again!