Assign Delay/Reverb for each tracks to controller ISSUE

Hey guys i wanted to set um my Midi Controller for better live performing with the digitakt, as i got an issue with this:

The FX wont be affected when im turning my potis - but why?

i assigned for example “FX feedback - Delay” CC88 on midi channel 4 (Track4 on my DT) or
“Amp delay send” CC8 to this poti and my digitakt wont do nothing with that.
Track Level Controll, Overdrive, etc. just works fine for each track.

can you help me?