STC3100, read to Control register is not returning the proper value

Hi all. I need a help regarding I2C write operation on one of the register of STC3100. There are two configurable registers, one is 'Mode register' and other is 'Control register'.I noticed that writing to the Control register is not working. When I write a value on control register, lets say 0x12 or any value,and then whenever I try to read that register it gives value as 0x10 everytime. Could you explain why it is happening so?