Installed but no heating

Last night I installed at my mother in laws house the V2 bridge and smart thermostat and extension kit replacing her current wireless thermostat and replaced the wireless receiver with the extension kit , I inputted details of wireless receiver into app and followed installation instructions and only had to move one wire from no 3 to no 4 and use the same backplate i turned on and activated pairing mode on bridge and held button down on extension kit to pair , it now has a flashing light every 2/3 seconds , the app says thermostat , bridge and extension kit is connected , I named the one zone lounge under thermostat and it’s says it’s connected to extension kit to call for heat . The combi boiler fires up when taps are turned on for hot water but I cannot get heat to come on , thermostat gives room temp and so does the app so I turned it up on thermostat and also on the app but the boiler does not fire up at all , bridge and extension kit seem on latest firmware but the smart thermostat is on 24.1 would this be a problem? Also I have tado in my own house with two zones and extension kit and alll works fine for last 3 years , when I change temp via app or Alexa it automatically changes on the smart thermostat but this does not happen on the one I installed last night. Am I missing something simple to get it to work , the only option I have is to get the mother in law to press the manual override button on top of extension kit as that clicks and then fires up the boiler to get heating on