WIndows 10 app, file transfer does not work properly

Have created a hybrid windows 10 app, which has functionality to upload and download image file. Uploading works perfectly fine but while download I can see the image being fetched from the server and I see that I have the right file from the server but it does not save it to windows phone storage.

Any sample or any pointers to get around the issue would be appreciated.

public DownloadFile(imageId): void {

    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, (fs) => {

        let filePath = fs.root.toURL();            

        fs.root.getFile(filePath, { create: false }, (entry) => {               
            entry.remove(() => {
                this.Download(imageId, fs);
            });
        },() => {
            this.Download(imageId, fs);
        });           
    });
}

private Download(imageId, fileSystem): void {
    let toastController = this._toast;
    let filePathOnServer = CommonConstant.Url.UploadPath + imageId;
    let fileTransfer = new Transfer();

    let imagePath = fileSystem.root.toURL() + imageId;

    fileTransfer.download(filePathOnServer, imagePath).then((entry) => {
        let toast = toastController.create({
            message: 'Your file has been downloaded successfully.' + entry,
            showCloseButton: true,
            closeButtonText: 'Ok'
        });
        toast.present();
    }).catch(() => {
        let toast = toastController.create({
            message: 'Your file could not be downloaded.',
            showCloseButton: true,
            closeButtonText: 'Ok'
        });
        toast.present();
    });
};