Rekordbox 7.1.0 crashes when I connect it to CDJ 3000 and DJM A9 mixer and DJM A9 crossfader can not be linked while playing video files with Rekordbox

Can Any one help me. I have updated latest versions of firmware for CDJ 3000 and DJM A9 but when I connect them with Rekordbox two thigs happens.

1. Rekordbox crashes many times and after opening it several times it starts working.

2. Rekordbox detects all hardware but Faders and crossfaders disappears in Rekordbox. so When I play video file my faders of DJM A9 are not linked with Rekordbox faders. so video does not change on output window with my DJM A9 mixer faders. 

I went into settings and checked my input/output section there internal mixer is grayed out. I am not able to select it. only external mixer is allowed.

Same when i connect it with DJM Nexus 900 my crossfaders and other faders gets linked with Rekordbox

Please help and guide me