Grrr... Spektrum DX2.0 won't talk to Flux ESC

Ok, this is pissing me off. Got a nice spanking new Spektrum DX2.0 for my Savage Flux to get rid of the crappy AM stock radio and i'm having issues with the thing. I can bind the radio to the receiver following SPektrums instructions, no problem them. When I try to do the Castle/HPI setting the throttle and braking point by holding down the throttle while powering up the ESC, I get the usual power up beeps, and it see's me holding the throttle, LED changes to green while doing so and does it little jingle till it changes to red and then I go to full brake for a few seconds and it supposed to jingle and then ask me to put it back to neutral and then its happy and done. Except the damn thing keeps blinking red with a beep at the same time. The steering works no problem but it just refuses to accept my throttle inputs. I tried changing throttle to reverse in the DX2.0 and very oddly, it allows me to do THAT and I brake becomes throttle and throttle becomes brake. WTF? So I plug in my old stock AM HPI radio and try again, and it works just like a charm.

Arrrrg, what am I doing wrong here?