Ansible - Handler not found on first attempt

Command run: sudo ansible-playbook site.yml --connection=local

Distributor ID: Ubuntu
Description:    Ubuntu 18.04 LTS
Release:        18.04
Codename:       bionic

ansible 2.5.5

I’m encountering this error only on my first run through after I change the following variable in the following file:

./group_vars/all

ntpserver: pool.ntp.org

TASK [common : Configure NTP file] **************************************************************************************************************
ERROR! The requested handler 'restart ntp' was not found in either the main handlers list nor in the listening handlers list


On my second run through, I’m having no issues:

TASK [common : Configure NTP file] **************************************************************************************************************
ok: [127.0.0.1] => {"changed": false, "checksum": "cc9e1a2d8777588fa4675e52f7ca7e352b23188a", "dest": "/etc/ntp.conf", "gid": 0, "group": "root", "mode": "0644", "owner": "root", "path": "/etc/ntp.conf", "size": 139, "state": "file", "uid": 0}

The folder and file structure I’m using is as follows:

https://github.com/ansible/ansible-examples/tree/master/lamp_simple_rhel7

./roles/common/handlers

- name: Restart NTP
  service: name=ntpd state=restarted`

./roles/common/tasks

---
- name: Install NTP
  apt: name=ntp state=present
  tags: ntp

- name: Configure NTP file
  template: src=ntp.conf.j2 dest=/etc/ntp.conf
  tags: ntp
  notify: restart ntp

- name: Install common packages
  apt: name={{ item }} state=present
  with_items:
    - fail2ban
    - ranger

- name: Start the NTP service
  service: name=ntp state=started enabled=yes
  tags: ntp

- name: Upgrade all packages to the latest version
  become: true
  apt:
    upgrade: yes
    update_cache: yes
    cache_valid_time: 86400 # one-day

- name: Configure NTP file
  template: src=ntp.conf.j2 dest=/etc/ntp.conf
  tags: ntp
  notify: Restart NTP