Can't get the example config to work

[Cybgak]

Hi all

I've managed to esptool working ok, backed up the factory firmware fine, installed esphome and can run the "esphome wizard" command to create a basic yaml file which then compiles fine when I try "esphome run basic.yaml".
The problem is whenever I try "esphome config configuration.yaml" I get an error saying the yaml syntax is incorrect.
I've only edited the file to change the WiFi ssid and password plus the OTA password, nothing else.
Any idea what I'm doing wrong?

Thanks in advance, Giles