Up to now, I have followed all the instructions on how to set I2C to work, and the situation now is I can see 68 via i2cdetect or 69 when I pull AD0 to VCC, so the linkage is fine. however, when I try to write bytes to registers, It fails. Nothing can be read either. The same code others use on Pi do not work. The blacklist is clear; I have root permission; I am sure the problem is due to pi, but so far I can not find where is it. Do anyone had such problem or know where the problem is?