Post Go back to editing

Missing MSB in LTC2292


I am using an LTC2292 and it seems I'm missing the 12th bit. Here is some background:

1) I have a differential op-amp (LTC6362) to do a DC conversion from 0V to 2V to +/-1V, with common mode voltage of 1.5V.

2) I am checking the output of the ADC with a logic analyzer and seeing that the MSB is stuck at 0. I would expect the MSB would be a 1 (I'm working in 2's complement) when the input is below 0V differential and the MSB would be 0 when the input is above 0V differential. 

3) I've checked solder connections, they look good

4) I've checked for shorts to GND, there is no short to ground on the MSB. 

Could I have a bad IC? Has anyone else experienced an ADC where a bit doesn't toggle?

Thanks in advance,