How to use the GraphDiff Entity Framework Code First

I have the following tables in my database:

The relationship is as follows:

• 1 Sale = > N Sales Details
• 1 Sale = > N Products Sales
• 1 Sales Details = > N Plots

I'm trying to make the method to add a new sale, however I'm not getting results, the method does not give error, but when I go check in the database, the record has not been saved.

The following is the code for my method:

public Venda LancamentoVenda(Venda obj)
{
    Db.UpdateGraph(obj, map => map
     .OwnedCollection(d => d.DetalhesVenda, r => r.AssociatedCollection(a => a.Parcelas))
     .OwnedCollection(x => x.ProdutosVendas));
    return obj;
}