I was successfully using the data logger with an uno, but had to migrate the project to Mega and was having no luck until I realized there's a typo in the datasheet. I feel very silly for missing it, but I wanted to share it. The data sheet says:
The ATmega2560 (VMA101) and ATmega32u4 Leonardo (VMA103) development boards do not use the same hardware SPI pin-out. If you are using one of these boards, please specify the pins used for SPI communication with the SD card. For the VMA202, these are pins 10, 11, 12 and 13. In the CardInfo sketch, modify line:
while (!card.init(SPI_HALF_SPEED, chipSelect)) {
to:
while (!card.init(SPI_HALF_SPEED,1,11,12,13)) {
That second line that yuo are changing TO should actually be
while (!card.init(SPI_HALF_SPEED,10,11,12,13)) {
-- this should have been obvious to me but I missed it for an embarrassingly long time. Changing the 1 to a 10 worked great.