Need Help with ltd EC1000 PIEZO

[arman]

Hi,
I've got my ltd EC1000p several months ago and everything was working fine. but the other day when I plugged my guitar in JACK 1 with mono cable the magnetic pickup didn't work. when I use the mag/piezo selector only piezo pickup have sound. It means I don't have the blend of both magnetic and piezo or magnetic pickup right now. please help me with this. what could be the problem?

it is good to know that when I use JACK 2 the magnetic pickups work fine and when I use a stereo cable in JACK 1, just piezo pick up have sound and nothing is coming out of magnetic pickups.

I appreciate any help on this.