what code should i add to the following code to check invalid username or password (1 Viewer)

Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
        Dim sPassword As String = ""
        'Connect to the server
        Using con As New System.Data.SqlClient.SqlConnection(cs)
            con.Open()
            Dim cmd As New System.Data.SqlClient.SqlCommand
            'Looks at the stored procedure
            cmd.Connection = con
            cmd.CommandType = CommandType.StoredProcedure
            'Look at the login table
            cmd.CommandText = "dbo.spLogin"
            'Put in the parameters of the query, its looks at the username texbox
            cmd.Parameters.Add("@Consultant", SqlDbType.NVarChar)
            cmd.Parameters("@Consultant").Value = Trim(Me.tbxUsername.Text)
            Using reader As SqlDataReader = cmd.ExecuteReader()
                Dim table As New DataTable
                table.Load(reader)
                'Is there a row with the right credentials?
                If table.Rows.Count = 0 Then
                    GoTo NotRecognised
                End If
                'Picks up the password
                For Each row In table.Rows
                    sPassword = Trim((row(0).ToString()))
                Next
            End Using
            con.Close()
        End Using
        Dim bLogin As Boolean = Trim(sPassword) = Trim(Me.tbxPassword.Text)
        If bLogin = True Then
            'Nice label stating its now connecting
            Me.lblLoading.Text = "Connecting to the server. Please wait ....."
            'Shows the homepage
            frmHomePage.Show()
            'Hides the login screen
            Me.Visible = False
            Exit Sub
        End If
        Me.Refresh()
NotRecognised:
        'Message box stating the user is not recognised
        MsgBox("You are not recognised by the system.")
    End Sub