Midi mapping - Traktor Kontrol Z1 - can't get the left and right faders to configure

For some reason when I select either of these, djay creates a new line, then when I select either turntable 1 or turntable 2, under ‘actions’ all I get is a list turntable options or effects, none of which is the option of making the fader control the volume of that turntable (as distinct from the gain).

I know this is possible, because I managed to see and select the right option earlier, but since then I’ve been experimenting with different configurations, and now I can’t access the option.

Please help!