hi everyone
in my other remote suppose i loose signal or switch it off, the throttle will go back to zero position but in the flysky it is just maintained in the position where i switched off the throttle, say i off it at 50% throttle , the throttle is  still maintained at 50%, it doesnt fall back to zero like with my avionic remote, so since the ppm signal is maintained at 50% even after loss of signal the apm 2.6 cannot enable the failsafe mode ( in my avionic say i loose signal, the ppm will drop below 1000, and the apm will enable return to land but im not able to do this with the flysky, since signal doesnt drop ), is there any other way of setting up the failsafe in ppm mode?

Did you upgrade the PPM encoder firmware on APM? Refer the links below for more info.

http://copter.ardupilot.com/wiki/common-autopilots/common-apm25-and-26-overview/common-ppm-encoder-apm2x-atmega32u2/

Well...I guess that should be the case. The receiver failsafe is when you lose signal from your Tx then your receiver outputs a default signal to the controller. When you bind your Tx and Rx just confirm that your transmitter switches are set to the controller failsafe positions. I guess its good to have your throttle above 10%, 50%. I did that in case of my naza failsafe config. Not sure about apm!

Yes it worked , thanks guys