Just because the cameras support TTL-external flashes doesn't mean they actually have TTL.
The D is the only body that has the TTL sensor, thus allowing it to use the built-in flash with any lens whether it's automatic or not.
Flashes on the DS, DL, and K series cameras all work the same. If an external flash is automatic, it'll work. It can also work in manual mode, but not in TTL.
I'll post some sample shots in a few minutes that prove my point
