Problem with line output via rekordbox

. The problem is that you can not stream the game on the recordbox, namely, you can not output the sound of the line output through the DJM 450 mixer , When you open the RB in the laptop mixer, the linear sound does not come out. And if you just play the music in the player through the line out and close the rekordbox, the sound comes out . How do I make a line out output line DJM

Sorry for the translation from Russian)))