I'm not sure if your radio works like mine, but you go into the programming screen for flaperons. Set it to adjust:
Master: CH. 6 (flaperons)
Slave: CH. 1 (right aileron)

Reverse that channel. Doing so will make the right aileron now go down when you rotate the flap knob. Do the same process again, only this time, use this:
Master: CH. 6 (flaperons)
Slave: CH. 6 (left aileron)

Now, both ailerons should go down when the flap knob is rotated. This is how it is done on my radio, hopefully it is simialr to yours.
-Andrew