Hello RoJec and thank you for your help
i just do some other research with your help and i find the way :
in preferences / audio, i have to select the "separation mono" in the place of "dual stereo"
Thanks a lot one more time RoJec !!!!!!
)))))
Problem solved !!!
PS : It seems to you right and left channel to create the cue so i was affraid to loose some quality and play only left or right channel but i dont see any change with or without the "separation mono" selected... ?