Исправьте код
Код:
foreach (DynamicEntity product in retrieved.BusinessEntities)
{
product["amount"] = newCrmDecimal(sum);
crmService.Update(product);
}
на
Код:
foreach (productpricelevel product in retrieved.BusinessEntities)
{
product.amount = new CrmDecimal(sum);
crmService.Update(product);
}