How to display a div, using *ngif else within a array in ionic4

I try to use *ngif and else to pass a false to boolean.The ngif is working but the else can not display the message. Hope some will help me.

  <div *ngFor="let nameList of nameList">
     <ion-row class="cont-text" *ngIf="nameList?.alertType ==='new'; else havedata === 'false'">
        &#8226; {{nameList?.description}} from {{NameList?.creationDate | date : 'dd MMM yyyy'}}<br>
   <div *ngIf="haveData === 'false'">
       <ion-row class="cont-text">No Problem is captured</ion-row>

Read the official docs for how this is supposed to be written.