I'm trying to add a new menuItem to the global navigation, following the example below:

https://world.episerver.com/documentation/developer-guides/CMS/user-interface/Extending-the-navigation/

Although then hitting these lines:

@Html.Raw(Html.ShellInitializationScript())
@Html.Raw(Html.GlobalMenu())

I get the following errors:

'HtmlHelper' does not contain a definition for 'ShellInitializationScript' and no extension method 'ShellInitializationScript' accepting a first argument of type 'HtmlHelper' could be found (are you missing a using directive or an assembly reference?)

Error CS1929 'HtmlHelper' does not contain a definition for 'GlobalMenu' and the best extension method overload 'MenuHelper.GlobalMenu(HtmlHelper)' requires a receiver of type 'HtmlHelper'

Entire code looks like this:

@using EPiServer.Framework.Web.Resources
@using EPiServer.Shell.Navigation





    

    

    
    @Html.Raw(ClientResources.RenderResources("ShellCore"))
    @Html.Raw(ClientResources.RenderResources("ShellWidgets"))

    
    @Html.Raw(ClientResources.RenderResources( "ShellCoreLightTheme"))
 
    
    @Html.Raw(ClientResources.RenderResources("Navigation"))

    
    @Html.Raw(ClientResources.RenderResources( "DojoDashboardCompatibility", new[] { ClientResourceType.Style }))
 


@Html.Raw(Html.ShellInitializationScript())
@Html.Raw(Html.GlobalMenu())

    @RenderBody()

Anybody knows why?