Djm 850 doesn't recognize midi in traktor but the audio is ok

When my Pioneer DJM 850 is connected to Traktor, it stops receiving MIDI information from the knobs, faders and buttons on the mixer. The audio is still heard, and I can control the EQ, gains, etc. on the mixer. The audio information appears in Traktor, but it is not possible to record and the MIDI values of the mixer do not appear. I have reinstalled the drivers, changed the cables and tried on other PCs and it always does the same thing. I tried to check the firmware version and it gives an error saying that the DJM 850 is not connected, but the audio works correctly.