[Stream it 2] OV7740 writing register

Hi,

I am using the sdk for camera and I am trying to command with serial interface  the register of camera OV7740 of stream it. I display the captured image on TFT panel provided by the kit.

I can write one time on the register of camera but the second time I can't write on the register. I must reset the camera to apply the modifications.  

Why I can write on the register one time and not 2 ?

It's hardware or software issue ?

Thanks for your reply