无法绑定到“ dateClass”，因为它不是angular7中“ mat-datepicker”的已知属性

我在应用程序中使用角度材质的日期选择器。我需要更改某些特定日期的颜色。为此，我使用的是mat-datepicker的'dateClass'属性。

html

    <mat-datepicker  [dateClass]="dateClass" #picker1 ></mat-datepicker>

零件

dateClass = (d: Date) => {
    const date = d.getDate();

    // Highlight the 1st and 20th day of each month.
    return (date === 1 || date === 20) ? 'example-custom-date-class' : undefined;
  }

错误

Can't bind to 'dateClass' since it isn't a known property of 'mat-datepicker'.
1. If 'mat-datepicker' is an Angular component and it has 'dateClass' input, then verify that it is part of this module.
2. If 'mat-datepicker' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.

我该如何解决这个问题？