sorting not yet working

ui/hv2-ui/src/app/app.module.ts

@@ -50,6 +50,7 @@ import { EnterPaymentComponent } from './enter-payment/enter-payment.component';
 import { HomeComponent } from './home/home.component';
 import { LedgerComponent } from './ledger/ledger.component';
 import { ErrorDialogComponent } from './error-dialog/error-dialog.component'
+import { MatSortModule } from '@angular/material/sort';
 
 registerLocaleData(localeDe)
 
@@ -102,7 +103,8 @@ registerLocaleData(localeDe)
     MatSelectModule,
     MatDatepickerModule,
     MatNativeDateModule,
-    MatExpansionModule
+    MatExpansionModule,
+    MatSortModule 
   ],
   exports: [
     MatMomentDateModule