LIPO batt charge with T9xr pro

I recently bought Turnigy 9xr pro and the S3 lipo safe batt you sell.
I want to charge it throw 9xr pro Transmitter. User manual says it can be done (charging < 300 mA, 12 V).but when I insert jack 12V (+ in pin) nothing happens. Does should be any signal on screen?. My firmaware is r212
about the FAQ video ...How charging LIPO batt, It says "is private" and I can not see it. Any idea?? thanks.