I'm using a domain-to-xml mapping to export some data. In my xsd I have an optional element "Prices" So I use a mapping microflow to decide wheter I return prices or not. Sometimes I want to return empty and sometimes a list of prices. When I return empty i'll get a error message: Could not find any objects to fill element 'Prices' I don't know why i'm getting this error, because in my xsd it's optional.