You DCT3416R cable box is not compatible with 3D TV your cable box needs to be swapped out for a compatible box. Once you have the correct box we will add the proper codes on your account and you will be able to view your 3D content.
I am also having an issue with split screen in 3D. When I go to select the top bottom for the 3D on the TV menu that option is grayed out thus I am stuck with the split screen. Has anyone expierenced this with Samsung? I have talked to Comcast and they have entered all the appropriate codes and I have the correct Cable box and HDMI cables.