In-app-purchase - LoadListingInformationAsync() doesnt work WP 8.1

I'm trying to create In-app-purchase in my WP 8.1 app, but i have problem with displaying all the in-app products available for purchase. I can not load listing information

I have this code, but when I try to load products, my application crashes on line var listing = await CurrentApp.LoadListingInformationAsync();

 var listing = await CurrentApp.LoadListingInformationAsync();
foreach (var product in listing.ProductListings)
{
  sb.AppendLine(string.Format("{0}, {1}, {2},{3}, {4}",
    product.Key,
    product.Value.Name,
    product.Value.FormattedPrice,
    product.Value.ProductType,
    product.Value.Description));
}
 MessageDialog msg = new MessageDialog(sb.ToString(),"asd");
    await msg.ShowAsync();

Thanks