Hi everyone,
I've noticed something strange using expression fields with ds merge
method in ado.net.
First of all, I create the schema via code. I've added also an
expression column in the Contracts Datatable:

col = ds.Tables["Contracts"].Columns.Add("CompanyName");
col.Expression = "Parent(CustomersContracts).CompanyName";

I don't use a data adapter to fill the dataset in fact
I need to call a web service method that returns a dataset.

Once I get the dataset from the webservice, I merge the data
retrieved in the Contracts Table.

ds.Merge(RetrievedDataSet);

If I try to read the expression field for the contracts retrieved
they're all DBNull.
This doesn't happen if I try to fill the dataset with a data adapter.
Any idea?

Do I need to call something before reading the expression column?

Thanks
Laura