How to use mattooltip?

How can I use mattooltip for here? It does not work.

 <div class="btn-edit-nounderline" matTooltipClass="custom-tooltip" 
 (click)="edit(row.widgetAccess)"  title=" 
 {{getTitle(row.widgetAccess.widgets.length)}}">

.custom-tooltip {
background-color:pink;
}

in ts file i have:

import { MatTooltipModule } from 

'@angular/material/tooltip/tooltip-module';

@NgModule({
 imports: [
 
 MatTooltipModule

]

})

getTitle(editWidgetsNum) {

return this.translate.instant('Edit_WidgetsNum', {n: editWidgetsNum});

}