Cannot create a Single-date Order ECO using a custom OData service

[elmo_ml]

In SAP Business ByDesign (byD), the OData Editor allows the creation of Custom OData Services. We are trying to create a new Engineering Change Order of type Single-date Order using a custom OData service but it is always failing. We have isolated the problem in a smaller custom OData service but the problem is still the same. We are able to create a Standard Order (so the service works) but if the creation of a Single-date Order is attempted, it is failing because the StartDate is required. Trying to add the StartDate into the custom OData service does not work: trying to call the service does not create the new ECO. Is there a way to create a Single-date Order ECO using a custom OData service?