DDJ-SZ can't hear master in headphones (neither in standalone mixer mode)

Hi

I bought pioneer ddj-sz and i updated the firmware to the 1.18 version. It works without issues on serato dj. The only problem is that i can't hear the master in the headphones. I thought maybe is an driver conflict, so i reinstalled serato, the audio driver and i checked the settings in the audio playback tab from windows control panel whithout succes. So i restarted the DDJ-SZ, i used an ipod to feed one channel in standalone mixer mode (it shows the VU meter on channel and master), the fader of the channel is up... so when i turn the knob anticlockwise (CUE) i can hear the sound from the channel in the headphones, when i turn it clockwise (MASTER) i can't hear nothing. The problem is only in the headphones, the master out is acting normally (used powered speakers to test).