probleme with charger/battery

hi
i bought 1 year ago a battery with charger.
the charger was out of service and you refunded it me. i bought a new one, imaxrc B6 compact charger.
then i had lot of things to do during all this time so can take care of my project.
now that i have time, i doing it again.
so when i plugg the batery , a turnigy 20-30c discharge - 2200 mah - 3 cell , all the charger's led stay green.
when i use a multimeter the voltage of batery for 1st cell is 3.89 - 2nd cell is 7.77 - 3rd is 11.65
but when i plugg the batery on aircraft, the flaps take a bad position and the motors doesn t work.
i need help to understand what happen please ...
thnx