ksoap2无法调用ItemInfo

Question

<soapenv:Body>
  <gos:SetReceiptRow>
     <gos:ReceiptUUID></gos:ReceiptUUID>
     <gos:ItemInfo>
        <gos:RowID></gos:RowID>
        <gos:Price></gos:Price>
     </gos:ItemInfo>
  </gos:SetReceiptRow>

当我尝试调用itemInfo属性时出现错误

我的语法是：

SoapObject item_obj = new SoapObject(Name_Space, "ItemInfo" );
item_obj.addProperty("Quantity",Quantity);
item_obj.addProperty("RowID",RowID);
item_obj.addProperty("Price",Price);

    SoapObject soapObject = new SoapObject( Name_Space, Method_Name);
    soapObject.addProperty("ReceiptUUID", ReceiptUUID);
    soapObject.addSoapObject( item_obj );