Please why am i getting error on this lines of code in Visual Basic

Imports System.Data.OleDb
Public Class Form1
    Dim con As New OleDb.OleDbConnection
    Dim da As New OleDb.OleDbDataAdapter
    Dim ds As New DataSet
    Dim conString As String
    Dim sql As String
    Dim maxRows As Integer
    Dim dsNewRow As DataRow

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Try
            conString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source='Contact_DB.accdb'"
            con = New OleDbConnection(conString)
            con.Open()
            sql = "select * from Person_TB"
            da = New OleDbDataAdapter(sql, con)
        Catch ex As Exception

        End Try