>yes, it is in spot metering mode. > >Are you hinting it will work in a different metering mode? >which?
Yes, TTL-BL is inhibited when in Spot Metering mode. It will work in either Matrix or Center Weighted.
The reason is that TTL-BL needs to know the ambient lighting across the whole frame (or at least most of it, like with CW), and spot will only give the light on the subject. This is also why Matrix metering ususally gives the best results with TTL-BL.