Help setting up

I’ve now set up my wireless doorbell 3 times! Tedious! Finally got as far as checking it, have a lovely clear picture of myself - in the dark! - Yes, it’s a good location. Twice now, I’ve put it into the bracket, 4 red lights flash on, a brief beep and a message to say it can’t connect to the chime unit!!

How did you set it up? Did you do so when the doorbell is close to the chime? It must be very close