Vaillant ecotec 618, vr65 & tado thermostat & extention kit

Is there any magic needed here.?

My tado app talks to the tado thermostat correctly but nothing happens with the zone valves.

If I reconnect the valiant vrt350 set to Max and use the Tado to intercept at lower temp them the valve works but is shortly "corrected" by the vrt350 to open. This " argument" continues wholst the vrt350 is connected. But the Tado does nothing if I unplug the vrt350?

Do I need anything specific here?