[Genius Live]

 try this

        Dim num As String = "SELECT MAX(ID_kh) + 1 AS Expr1 FROM Daily"

        Dim OleDBDR As OledbDataReader

        With OleDBC

            .Connection = con

            .CommandText = num

        End With

        OleDBDR = OleDBC.ExecuteReader

        If OleDBDR.HasRows Then

            While OleDBDR.Read

                If OleDBDR.IsDBNull(0) = True Then

                    TextBox1.Text = 1

                Else

                    TextBox1.Text = (OleDBDR.Item("Expr1"))

                End If

            End While

        Else

            TextBox1.Text = 1

        End If