Navigate through records of a database

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VB

I have 3 text boxes that retrieve data from the database and 4 buttons fist, previous, next and last that help me to navigate through the records of the table.
But I have a problem with the code of the button previews and next.
Because when I execute the application, the next button takes only one value (row=2) and always when I press the next button it leads me to the second record of the table.
the same thing happens with the previous button, it takes only the first record of the table.
Please tell me what I have made wrong to my code?

Imports System.Data.OleDb
Imports System.Data.SqlClient

Public Class default
    Inherits System.Web.UI.Page

    Dim Sql As String

    Dim inc As Integer = 0
    Dim ds As New DataSet
    Dim MaxRows As Integer
    Dim SQLConnection As Object

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       
        NavigateRecords()
    End Sub

    Private Sub NavigateRecords()

        Dim con As New OleDb.OleDbConnection
        Dim strCon As String = "Provider=SQLOLEDB; Data Source=192.168.131.72; Initial Catalog=Flex; User ID=sa; Password="

        con.ConnectionString = strCon

        con.Open()
        Dim ds As New DataSet
        Dim da As OleDb.OleDbDataAdapter

        Sql = "SELECT * FROM Customer"

        da = New OleDb.OleDbDataAdapter(Sql, con)
        da.Fill(ds, "Person")

        con.Close()
        MaxRows = ds.Tables("Person").Rows.Count
        txt_name.Value = ds.Tables("Person").Rows(inc).Item("2")
        txt_surname.Value = ds.Tables("Person").Rows(inc).Item("3")
        txt_city.Value = ds.Tables("Person").Rows(inc).Item("4")
    End Sub

    Protected Sub btn_next_Click(sender As Object, e As EventArgs) Handles btn_next.Click
        If (inc <> (MaxRows - 1)) Then

            inc = inc + 1

            NavigateRecords()

        End If
    End Sub

    Protected Sub btn_first_Click(sender As Object, e As EventArgs) Handles btn_first.Click
        If (inc <> 0) Then

            inc = 0

            NavigateRecords()

        End If
    End Sub

    Protected Sub btn_previews_Click(sender As Object, e As EventArgs) Handles btn_previews.Click

        If (inc > 0) Then

            inc = inc - 1

            NavigateRecords()
        End If
    End Sub

    Protected Sub btn_last_Click(sender As Object, e As EventArgs) Handles btn_last.Click
        If (inc <> (MaxRows - 1)) Then

            inc = MaxRows - 1

            NavigateRecords()

        End If
    End Sub

End Class