They should be compatible, as some of our customers in this forum has also used D3S with V6 II.
In camera system, please select AUTO to let the V6 II auto detect the camera. Half press the camera's shutter release and switch on the V6 II at the same time. The V6 II will auto detect your D3s. If it succeeds, you will find the little "N" inside the camera logo. And you are good to go.
If not, please check the hot shoe connection and ensure that the hot shoe is firmly locked and fully inserted. And start the auto-detect again.
Comments
In camera system, please select AUTO to let the V6 II auto detect the camera. Half press the camera's shutter release and switch on the V6 II at the same time. The V6 II will auto detect your D3s. If it succeeds, you will find the little "N" inside the camera logo. And you are good to go.
If not, please check the hot shoe connection and ensure that the hot shoe is firmly locked and fully inserted. And start the auto-detect again.