Check your keyboard's Local On/Off setting as that will cause the issue you have. Make sure it is set to ON
I just took a look at the KN7000 manual it says "On the MIDI MENU display select PART SETTING". There is a LOCAL On\Off setting for RIGHT1 RIGHT2 and LEFT and they should all be ON for normal use. If they are ON then you may have a hardware issue. Though I would first try turning them OFF then back ON again.