Template variables not updating in Page view

Ionic Framework ionic-v3
1

I have issue in displaying the values from ts to html.

Please find the code snippets below:

HTML:

 <ion-list inset>            
        <ion-item>
          <ion-label>Date :</ion-label> {{salesdate}}
        </ion-item>
        <ion-item>
          <ion-label>Sales Type :</ion-label> {{salestype}}
        </ion-item>             
        <ion-item>
          <ion-label>Card No.:</ion-label> {{cardno}}
        </ion-item> 
        <ion-item>
          <ion-label >Party:</ion-label> {{party}}
        </ion-item>     
        <ion-item>
          <ion-label >Godowm:</ion-label> {{godown}}
        </ion-item>     
 </ion-list>

TS:

 export class SaleViewPage {

    salesdate:string;
    salestype:string;
    billno:string;
    cardno:string;
    party:string;
    godown:string;  

   constructor(public navCtrl: NavController, public navParams: NavParams,
   private dataservice: DataService) {
   this.billno = this.navParams.get('billno');  
  }

  ngOnInit() { 
     this.loadSales(this.billno);         
  }

  public loadSales(billno){
    this.dataservice.getSales(billno).subscribe(result => {
       if (result != null)
       {
       this.salesdate = result.billdate;
       this.salestype = result.sname;
       this.cardno    = result.cardno;
       this.party     = result.party;
       this.godown    = result.gname;
       }
    },
    error => {      
    });
   }

I can see in the console log that result has values and the variables are assigned without any issues.

It is the values are not showing in the Page.