Not compatible message could randomly appear in these situations exclusive to iPad air.
1. Plug card reader before unlocking iPad air
2. Memory card is not inserted far enough
3. Continuous use of iPad air. Once restart, popup message will disappear.
We are working hard to tackle this issue to meet apple high performance standard.
*There is no incompatible error message on iPad 4/iPad mini (with retina display) while using this camera connection kit.