I2C.scan missing value

[ketchup T]

This post is deleted!

[ketchup T]

You have reason, the problem related to my sensor. I plug the cables GND and 3V3 to the ESP kit instead of Expansion board, and it works. I tried to connect another sensor to Expansion Board, and it also works! Now I can receive [26,80]. Thanks you. Because the problem is not about software but hardware, so I will close this topic. Thanks for your help anyway

[robert-hh]

@ketchup-T That's indeed strange. You should expect [26, 80] as result. Are proper pull-up sensors in place? And does the sensor work on 3.3V?