Have you tried Live View when using the DSTE grip? MustangNYC has a reviewed the DSTE and he gets "Err" with 2 different DSTE grips;
Ref: "Nikon D800 DSTE Battery Grip D4 Battery in D800"
Despite being a Chinese made copy of the now $350 Nikon D800 Battery Grip, I can't really tell the difference between the two. The quality of the plastic seems identical, the rubber is the same grippy material that you find on the original and all of the parts open and close with the same fit as the far more expensive Nikon. On the camera, everything works as well as you could expect it too. I have had this on the camera for the last two weeks nearly non-stop and I have yet to have a single issue with its functionality. The buttons work well, and I have never experienced any issues with the batteries not showing their proper charge.