Ipv4_address must be a mapping docker-compose

Docker Engine Compose
1

This is my compose file but it does not work correctly

version: "3"
services:
 chec:
  image: 703004cee093
  hostname: chec
  container_name: chec
  ports:
   - 8080:5000/tcp
   - 8000:8000/tcp
  networks:
    monitoring:
    ipv4_address: 172.12.12.50
  volumes:
   - type: bind
     source: /home/monitoring/chec
     target: /omd/sites
   - /etc/localtime:/etc/locatime:ro

It is showing follow error :

services.chec.networks.ipv4_address must be a mapping

2

That’s because the indention is wrong, see: compose file specification - ipv4_address