Ionic 3 onProgress not working

I try this code but the function not working

downloadFile(){

const fileTransfer: FileTransferObject = this.transfer.create();

fileTransfer.onProgress((progressEvent) => {
// console.log(progressEvent);
if (progressEvent.lengthComputable) {
var perc = Math.floor(progressEvent.loaded / progressEvent.total * 100);
this.test = perc + “% loaded…”;
} else {
if (this.test == “”) {
this.test = “Loading”;
} else {
this.test += “.”;
}
}
});

fileTransfer.download(this.reUrl, this.file.externalDataDirectory + this.allData.title +'.mp4').then((entry) => {
 
  this.showTos.ShowToast(entry.toURL());
  //console.log('download complete: ' + entry.toURL());
}, (error) => {
  this.showTos.ShowToast(error);
  // handle error
});

}

Any Idea about this or any other way