AOUT NG : only half expected voltage in bipolar

By julienvoirin in Testing/Troubleshooting,
dear boxers i've got a hard problem I've made the Aout-ng module of smash tv, in a midibox cv. I use a bipolar PSU -12V + 12v to supply aout ng on J3 (+12, gnd , -12v). i supply the core (completly stuffed) at J1 with gnd and +12V pin of the bipolar PSU. When in unipolar mode, i have the expected range (from zero to 10,67V). it's how i calibrated the gain before the opamp, using P1. Then i switched to bipolar mode, and set P9 (on channel CV1) to adjust the "middle" (in mb cv menu). I well have zero volt. BUT, when i set "min" and "max" i only have -2,76V and +2,76V. I should have -5V, +5V. I have this problem on all the channels. If i remove the gnd from Aoutng J3, and supply the core with a wallmart (9V DC) , i got a bias of +10V on my min and max voltages in bipolar ( min = 7V, middle= 10V, max = 12,56V ) ! The ground of Core is connected to the ground of AoutNG. So what's the problem ???
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