PrimeNG - SideMenu znika przy dodaniu gałęzi

Gdy nie ma podkategorii w menu to wszystko jest ok:

import { Component, OnInit } from '@angular/core';

import { MenuItem } from 'primeng/api'

@Component({
  selector: 'app-panel-menu',
  templateUrl: './panel-menu.component.html',
  styleUrls: ['./panel-menu.component.css']
})
export class PanelMenuComponent{

  items: MenuItem[];

  ngOnInit() {
      this.items = 
      [
        {label: 'Dashboard', icon: 'pi pi-fw pi-globe'},
        {label: 'Buildings', icon: 'pi pi-fw pi-home'},
        {label: 'Land', icon: 'pi pi-fw pi-table'},
        {label: 'Units', icon: 'pi pi-fw pi-th-large'}, 
        {label: 'Inbox', icon: 'pi pi-fw pi-envelope'}, 
        {label: 'Calendar', icon: 'pi pi-fw pi-calendar'}, 
        {label: 'Contacts', icon: 'pi pi-fw pi-users'}, 
        {label: 'Settings', icon: 'pi pi-fw pi-list'},   
      ];
  }
}

Natomiast gdy dodam podkategorię, menu przestaje działać:

import { Component, OnInit } from '@angular/core';

import { MenuItem } from 'primeng/api'

@Component({
  selector: 'app-panel-menu',
  templateUrl: './panel-menu.component.html',
  styleUrls: ['./panel-menu.component.css']
})
export class PanelMenuComponent{

  items: MenuItem[];

  ngOnInit() {
      this.items = 
      [
        {label: 'Dashboard', icon: 'pi pi-fw pi-globe', items:[
          {label: '2'}
        ]},
        {label: 'Buildings', icon: 'pi pi-fw pi-home'},
        {label: 'Land', icon: 'pi pi-fw pi-table'},
        {label: 'Units', icon: 'pi pi-fw pi-th-large'}, 
        {label: 'Inbox', icon: 'pi pi-fw pi-envelope'}, 
        {label: 'Calendar', icon: 'pi pi-fw pi-calendar'}, 
        {label: 'Contacts', icon: 'pi pi-fw pi-users'}, 
        {label: 'Settings', icon: 'pi pi-fw pi-list'},   
      ];
  }
}

Ktoś wie co robię nie tak?

Naciśnij F12 w Chrome i zobacz czy nie ma błędów w zakładce console