I changed a few things in your database to make it work.
1: If you load a new 'workorder' for a 'service', the 'workorder' does not yet exist. The query 'Workorder' will not show anything. You can not add the workorder, because it does not know to which 'serviceID' it need to link. Therefor I changed the query to use LEFT JOIN's:
Code:
SELECT Customer.FirstName, Customer.LastName, Customer.Contact, Vehicle.Make, Vehicle.Model, Vehicle.LicensePlate, Vehicle.VIN, Vehicle.EngineType, Vehicle.EngineVolume, Vehicle.EnginePower, Service.Kilometers, Service.ServiceID, tWorkOrder.WorkOrderID, tWorkOrder.WorkOrderNumber, tWorkOrder.DateOfReceivement, tWorkOrder.DateOfHandOver, tWorkOrder.DescriptionOfWork
FROM ((Customer LEFT JOIN Vehicle ON Customer.[CustomerID] = Vehicle.[CustomerID]) LEFT JOIN Service ON Vehicle.[VehicleID] = Service.[VehicleID]) LEFT JOIN tWorkOrder ON Service.ServiceID = tWorkOrder.ServiceID;
What it does is,when you open the form selecting the ServiceID, it will show the serviceID even if the WorkorderID does not yet exist. Now, if you start adding data, it will create a workorder linking to your ServiceID.
2: From the service form the button did not work to open the workorder. I changed the WHERE condition in the macro from '
="[ServiceID]=" & [ServiceID]' to '
"[ServiceID]=" & [ServiceID]'. The '=' sign at the beginning was double.