I can't scratch. Why not?

Vinyl mode might be turned off (normal mode).

If you spin the top of the jog wheel when Vinyl mode is turned off, the playback speed will be affected (Pitch Bend feature). Touch [JOG MODE] on the [WAVEFORM] screen to switch to Vinyl mode.

For details, see [Using the jog wheel] in the Instruction Manual.

You can read the Instruction Manual [here].