title: Angular7: MatButtonModule doesn't load
body: <p>I begin with Angular7 and Material fwk, I load some modules on my app module :</p>
  
  <pre><code>import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
  import { MatButtonModule, MatCheckboxModule, MatToolbarModule, MatSidenavModule, MatListModule, MatIconModule, MatSelectModule } from '@angular/material';
  import { AppRoutingModule } from './app-routing.module';
  import { AppComponent } from './app.component';
  
  @NgModule({
    declarations: [
      AppComponent
    ],
    imports: [
      BrowserModule,
      BrowserAnimationsModule,
      AppRoutingModule,
      MatButtonModule,
      MatToolbarModule,
      MatListModule,
      MatIconModule,
      MatSidenavModule,
      MatCheckboxModule,
      MatSelectModule
    ],
    providers: [],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>
  
  <p>All these modules are loaded and I can use them, except mat-button </p>
  
  <pre><code>&lt;mat-toolbar class="menu" color="primary"&gt;
    &lt;mat-icon&gt;public&lt;/mat-icon&gt;
    &lt;div class="fill-space"&gt;&lt;/div&gt;
    &lt;mat-button&gt;
      &lt;mat-icon&gt;explore&lt;/mat-icon&gt;
    &lt;/mat-button&gt;
  &lt;/mat-toolbar&gt;
  </code></pre>
  
  <p>I got this error : </p>
  
  <pre><code>Uncaught Error: Template parse errors:
  'mat-button' is not a known element:
  1. If 'mat-button' is an Angular component, then verify that it is part of this module.
  2. If 'mat-button' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message
  </code></pre>
  
  <p>I've try differents tricks, delete/clean and reinstall but all the material components works except mat button.</p>
  
  <p>Material and Angular in package.json are in 7.0.1 version</p>
  
  <p>Thank you for your time/help</p>