Object reference not set to an instance of an object

Hola foro
Queriendo rellenar un combobox, mi codigo me arroja este error:

Object reference not set to an instance of an object

He buscado en Google, pero ninguno ofrece solucion a esto.
Alguna sugerencia?
Saludos.

Mi codigo:

Dim w_dsClient as new DataSet --esta a nivel de clase

Dim strSQL As String
strSQL = "SELECT * FROM County ORDER BY CountyName"

Dim w_daTable As New OleDbDataAdapter(strSQL, objGlobal.getConnectionString)
w_daTable.Fill(w_dsClient, "County")

cboCounty.DataSource = w_dsClient.Tables.Item(0) --el error sucede ACA
cboCounty.DisplayMember = "CountyName"
cboCounty.ValueMember = "CountyID"