al final en next del for pone a que variable te referis
Código vb:
Ver originalFor i = 0 To adataset.Tables("[MS Access;DATABASE=" & TextBox1.Text & "].[Per]").Rows.Count - 1
ni = adataset.Tables("[MS Access;DATABASE=" & TextBox1.Text & "].[Per]").Rows(i).Item("N").ToString
For x = 0 To adataset1.Tables("Per").Rows.Count - 1
nx = adataset1.Tables("Per").Rows(x).Item("N").ToString
Next x
Next i