Uncaught Error: Template parse errors: Can't bind to 'dataSource' since it isn't a known property of 'table'

hello when am trying to add the material data table i found this error : Uncaught Error: Template parse errors: Can't bind to 'dataSource' since it isn't a known property of 'table'.

 - my material version : "@angular/material": "^6.2.1"
 - my angular version : "@angular/core": "^6.0.5",

here is my module.ts

import {BrowserAnimationsModule} from '@angular/platform-browser/animations';
import {MatButtonModule, MatCheckboxModule} from '@angular/material';
import { MatTableModule , MatSortModule } from "@angular/material";

here is my component.ts file

import {Component, OnInit, ViewChild} from '@angular/core';
import {MatSort, MatTableDataSource} from '@angular/material';

@Component({
  selector: 'app-government-index',
  templateUrl: './government-index.component.html',
  styleUrls: ['./government-index.component.scss']
})
export class GovernmentIndexComponent implements OnInit {
  displayedColumns = ['position', 'name', 'weight', 'symbol'];
  dataSource = new MatTableDataSource(ELEMENT_DATA);

  @ViewChild(MatSort) sort: MatSort;

  ngOnInit() {
    this.dataSource.sort = this.sort;
  }
}

export interface PeriodicElement {
  name: string;
  position: number;
  weight: number;
  symbol: string;
}

const ELEMENT_DATA: PeriodicElement[] = [
  {position: 1, name: 'Hydrogen', weight: 1.0079, symbol: 'H'},
  {position: 2, name: 'Helium', weight: 4.0026, symbol: 'He'},
  {position: 3, name: 'Lithium', weight: 6.941, symbol: 'Li'},
  {position: 4, name: 'Beryllium', weight: 9.0122, symbol: 'Be'},
  {position: 5, name: 'Boron', weight: 10.811, symbol: 'B'},
  {position: 6, name: 'Carbon', weight: 12.0107, symbol: 'C'},
  {position: 7, name: 'Nitrogen', weight: 14.0067, symbol: 'N'},
  {position: 8, name: 'Oxygen', weight: 15.9994, symbol: 'O'},
  {position: 9, name: 'Fluorine', weight: 18.9984, symbol: 'F'},
  {position: 10, name: 'Neon', weight: 20.1797, symbol: 'Ne'},
];

here is the link that am trying to follow : https://material.angular.io/components/table/overview