Listbox not correctly picking the item I am choosing

    Sub FillItemsList()
        Dim connectionString As String = "Data Source=.;Initial Catalog=Shop;integrated security=true"
        Dim dt As New DataTable()

        Using connection As New SqlConnection(connectionString)
            Dim sql As String = "SELECT PhoneName,PhonePrice FROM SmartPhones"
            Using adapter As New SqlDataAdapter(sql, connection)
                adapter.Fill(dt)
            End Using
        End Using

        ListBox1.DataSource = dt
        ListBox1.DataTextField = "PhoneName"
        ListBox1.DataValueField = "PhonePrice"
        ListBox1.DataBind()

    End Sub
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
        Label2.Text = Request.QueryString("Name").ToString()

        If Not Page.IsPostBack Then
            FillItemsList()
        End If
        
    End Sub


    Protected Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
        sum = 0 'reset sum to 0
        For Each i As Integer In ListBox1.GetSelectedIndices
            Dim CurrentItem As ListItem = ListBox1.Items(i)
            sum = sum + CInt(CurrentItem.Value)
            Items1 = Items1 + " | " + CStr(CurrentItem.Text)
        Next
        Label3.Text = Items1
        Label1.Text = sum


    End Sub

<asp:ListBox ID="ListBox1" runat="server" SelectionMode="Multiple" autopostback="true"</asp:ListBox>