USPS Shipping Error

When first class shipping is enabled in NopSolutions.NopCommerce.Shipping.Methods.USPS.USPSStrings, i get the following error:

USPS Error returned: Error Desc: Invalid First Class Mail Type.USPS Help Context: 1000440.

Works fine when I comment it out.  Also doesn't seem to work if 'ALL' is selected.

To fix this, in USPSComputationMethod.cs, we added the FirstClassMailType element to the XML, as follows:

    sb.AppendFormat("<Service>{0}</Service>", element);
  
    // add next two lines to fix "Invalid First Class Mail Type" error
    if (element == "First Class")
        sb.AppendFormat("<FirstClassMailType>Parcel</FirstClassMailType>", element);

Seems to be needed in versions 1.5 and 1.6 of the code base.