Hopefully someone can help.

I have a Honeywell Lyric T6R Smart Thermostat (wireless) and trying to connect it correctly to my Worcester 35Cdi Combi Boiler.

The wiring diagram mentions connecting it , via A & B on Receiver Box tp T1 & T2 on the boiler, which I think means Ls & Lr (see B in photo )

Heat demand lights up on the receiver box but boiler doesn't fire up.

Is the diagram wrong or have I connected the wires to the wrong terminals on the boiler? I HAVE removed the jumper link bween Ls & Lr.