Table FillSchema Method

Hi,

Sorry if these is not the right forum for this:

I€™m using the data adapter method FillSchema works fine in MS Access but SQL Server Express Edition it doesn€™t get the primary key of the table. For example if I try to use the Find method of the dataset I get this error €œTable doesn't have a primary key€? but in MS Access these do not happen.

This is the code that I€™m using:
Dim sql As String = "SELECT admin.rents.id, admin.rents.transaction_id, admin.rents.item_id, admin.rents.description, admin.rents.due_date, admin.rents.return_date, "
sql &= "admin.rents.amount_to_pay, admin.rents.paid_amount, admin.rents.tax, admin.rents.type, admin.rents.deposit_id "
sql &= "FROM admin.rents INNER JOIN "
sql &= "admin.transactions ON admin.rents.transaction_id = admin.transactions.id "
sql &= "WHERE admin.transactions.customer_id=?; "

RentsDA = New OdbcDataAdapter(sql, cn)
With RentsDA.SelectCommand
.Parameters.Add(New OdbcParameter("@customer_id", OdbcType.Int)).Value = TextBox1.Text.Trim
End With
RentsDA.FillSchema(ds, SchemaType.Source, "Rents")
RentsDA.Fill(ds, "Rents")

It's because of the joins?
I need to configure something in the sql server?
What is the problem?