front speakers wont work through auxillary, help?

hey i have a volkswagen polo with a Kenwood KDC-W7037 in it.
i have custom speakers installed in the back of the car.

now the radio works through all the speakers just find when i activate the 2 zone on the remote.

but when i come to play my auxillary jack (my ipod) the music wont work through the front speakers, only the custom ones in the back. AND the radio plays at the same time as my ipod!!!

i am new to all this audio stuff so i guess im a noob, can someone explain to me how to fix this? thankyou?? =]]