title: Attempted to open an MatDatepicker with no associated input
body: <p>I have defined this MatDatePicker:</p>
  
  <pre><code> &lt;input #creatoDal matInput [matDatepicker]="creatoDal"
                              (focus)="creatoDal.open()" readonly&gt;
                          &lt;mat-datepicker-toggle matSuffix [for]="creatoDal"&gt;&lt;/mat-datepicker-toggle&gt;
                          &lt;mat-datepicker #creatoDal&gt;&lt;/mat-datepicker&gt;
  </code></pre>
  
  <p>It seems to me that I've bound the reference correctly, but when clicking on the datepicker it doesn't open and it gives me the following error:</p>
  
  <blockquote>
    <p>Error: Attempted to open an MatDatepicker with no associated input.
        at MatDatepicker.push../node_modules/@angular/material/esm5/datepicker.es5.js.MatDatepicker.open</p>
  </blockquote>