I cannot control Serato DJ's DECK using control CD/Vinyl.

Check the following items:

1. Is the firmware the latest version?
The firmware is the system software inside the unit. To use this unit more comfortably, always use the latest version.
The latest firmware can be obtained from the following AlphaTheta support page.
DJM-S9　Firmware

2. Are the settings and connections correct?
For details on the settings and connections, see "Using the DVS system" in the operating instructions.
The operation instructions can be obtained from the following AlphaTheta support page.
DJM-S9　Manual

3. Is the Serato DJ version correct?
If you use control CD/Vinyl to control DECK, your Serato DJ version must be 1.8.0 or later.
Obtain the latest Serato DJ software from the following Serato website.
http://serato.com/