Search for a value in a dataset/datatable

I have Dataset DS.
I have Datatable DT.
I have column ValueA, ValueB, ValueC in the DT.

Now I want to input ValueA and ValueB and return ValueC.

Found this option:
DS.DT.Rows.Find(expression)

but it requires primary keys, don't have them yet.

Found this option:

DS.DT.Select(expression)

But when I use this code:

Dim myrow() As DataRow

myrow = DS.DT.Select("ValueA = '23' and ValueB = '26'") DataGrid2.DataSource = myrow

Then it returns the 'layout' of myrow;

RowError RowState ItemArray HasErrors Table


Any idea on how to get ValueC in a string or integer from myrow?