Arduino logging shield woes

Worked with John Cao today trying to continue the work that Hamza and I did on Friday.

What we did on Friday:
We used a stack (Arduino UNO base, then Adafruit Datalogger shield on top, then ARD-LTC2499 shield on top of that) and connected a sensor (Gaseous Compounds NO2 sensor, which has two HI outputs and two LO outputs). SD card used was SDHC 32GB.
We powered the sensor through the 3.3V port on Arduino pins (SPI bus??), and connected all the GRND to various ground ports.
Then we put the HI inputs to the analog channels (A1 and A2) on the ARD-LTC shield. We used the basic example sketch that came with the ARD-LTC and its corresponding libraries.
Hamza set the output of the gaseous sensor to one of the pins and viewed the output on the serial monitor. He was getting 1's not the actual data, so we think it was right, but we're not sure.

What we did today (Monday):
We used the same stack described above, and tried get the SD card to work.
We used the "Datalogger" sketch example, set the CS pin to 10, and got the error "Card missing" telling us that it didn't initialize properly.
We used the SD card adapter to plug into my laptop and reformatted the card. We got the same error when we tried again.
We used the "Checkcard" sketch example, and got the same initialization error.
We used a different stack (Arduino UNO base, then Adafruit GPS+logger shield on top) and ran the "Checkcard" sketch example on this stack (which had a different SD card in it, SDHC 8GB) and it worked, revealing the file names and dates stored on the card.
We switch in the 32GB card to this new stack, and the "Checkcard" sketch example also worked.
We did NOT do any work with the MUX/ADC shield or code. Plan is to do that tomorrow with Hamza again.


So... It looks like there is an hardware defect with the Datalogger shield. Unless there is some connection the shield that we have to make in order for it to work that we are forgetting?? Which is a bummer, because it seems like we should buy more Datalogger shields, but what if they're just bad-quality shields with bad manufacturing? Or what if they're so delicate that we will regularly break them? I don't think this should be such a big mystery...

-Rachel Gamblin