Regarding header footer in another module in angular – Blancer.com Tutorials and projects

I am a new of Angular. I created header, footer and sidebar. And I was create dashboard component if I use in this dishoard component its works good. So it is working in component. then I created a module for employee. if i use Header Footer Sidebar in this employee module means its shows error

If ‘app-header’ is an Angular component, then verify that it is part of this module.
If ‘app-header’ is a Web Component then add ‘CUSTOM_ELEMENTS_SCHEMA’ to the ‘@NgModule.schemas’ of this component to suppress this message.


src/app/employee/list-employee/list-employee.component.ts:5:16
  5   templateUrl: './list-employee.component.html',
                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Error occurs in the template of component ListEmployeeComponent.


Error: src/app/employee/list-employee/list-employee.component.html:2:1 - error NG8001: 'app-sidebar' is not a known element:
1. If 'app-sidebar' is an Angular component, then verify that it is part of this module.
2. If 'app-sidebar' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.

2 <app-sidebar></app-sidebar>

src/app/employee/list-employee/list-employee.component.ts:5:16
5 templateUrl: ‘./list-employee.component.html’,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Error occurs in the template of component ListEmployeeComponent.

Error: src/app/employee/list-employee/list-employee.component.html:514:9 – error NG8001: ‘app-footer’ is not a known element:

If ‘app-footer’ is an Angular component, then verify that it is part of this module.
If ‘app-footer’ is a Web Component then add ‘CUSTOM_ELEMENTS_SCHEMA’ to the ‘@NgModule.schemas’ of this component to suppress this message.

514
~~~~~~~~~~~~

Please help me to sort out this error.