Object reference not set to an instance of an object.

Line 37:         dt = ds.Tables("Tabel")
Line 38:         If dt.Rows.Count > 0 Then
Line 39:             Response.Redirect

Protected Sub ButLog_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles ButLog.Click
        Dim con As New SqlConnection
        Dim cmd As New SqlCommand("log1")
        Dim ADD As New SqlDataAdapter
        cmd.CommandType = CommandType.StoredProcedure
        Dim ds As New DataSet
        Dim dt As New DataTable
        con.ConnectionString = "Server=.;Database=log;User Id=sa; Password=123;"
        cmd.Connection = con
        ADD.SelectCommand = cmd

        ' Dim cmd2 As SqlCommand = New SqlCommand("SELECT * FROM [pationt] WHERE [pationt_usermane] = '" & txtUser.Text & "' AND [pationt_pass] = '" & txtpass.Text & "'", con)
        'Dim dr As SqlDataReader = cmd2.ExecuteReader
        ' the following variable is hold true if user is found, and false if user is not found
        Dim userFound As Boolean = False
        ' the following variables will hold the user first and last name if found.
        cmd.Parameters.Add("@Username", SqlDbType.VarChar)
        cmd.Parameters("@Username").Value = TxtUser.Text
        cmd.Parameters.Add("@Password1", SqlDbType.VarChar)
        cmd.Parameters("@Password1").Value = TxtPass.Text
        con.Open()
        'ADD.Fill(ds, "Tabel")
        con.Close()
        'dt = ds.Tables("Tabel")

        If > 0 Then
            Response.Redirect("welcome.aspx")
        Else
            MsgBox("Sorry, username or password not found", MsgBoxStyle.OkOnly, "Invalid Login")
            ' ClientScript.RegisterStartupScript(Page.[GetType](), "validation", "<script language=")
        End If
    End Sub