Can't get SB910 into TTL mode...
I don't have the D800 but it might have to do with the how you have your metering set; Spot, Matrix, Center weighted. I seem to remember running into this once on the D700 but can't remember which of the settings caused it.
Aliso Viejo, CA
|I am an Elephant by Bibix|
from An A to Z of Subjects- Week 5, E
|Mossy forest panorama by Jill Hancock|
from Your point of view
|Ship Moon and Stars by LJJohnston|
from For creative newbies only..