Dynamically created buttons not calling function on postback - asp.net

Question

In my visual basic web application I have a list of generated buttons that are supposed to allow the download of a file on click.
I had the example working with generated buttons on pageload, but all of a sudden the download function stopped getting called on post back, and now all the button click does (for any of the buttons) is cause a page post back.
My code:
Public folder As String
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
folder = "Main"
PopulateFiles(folder)
End If
End Sub
Protected Sub PopulateFiles(ByVal folder As String)
Dim myConnection As SqlConnection
Dim conString As String = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString
Dim myCommand As SqlCommand
Dim myDataReader As SqlDataReader
Dim text As String
Dim size As Decimal
Dim name As String
Dim type As String
Dim id As Integer
folderName.Text = folder
container.Controls.Clear()
myConnection = New SqlConnection(conString)
myConnection.Open()
myCommand = New SqlCommand("Uploads_GetAllFiles", myConnection)
myCommand.CommandType = CommandType.StoredProcedure
myCommand.Parameters.AddWithValue("#folder", folder)
Try
myDataReader = myCommand.ExecuteReader()
If myDataReader.HasRows Then
Do While myDataReader.Read()
name = myDataReader.Item("Name")
type = myDataReader.Item("Type")
id = myDataReader.Item("File_ID")
size = Math.Round(myDataReader.Item("Size") / 1000, 2)
container.Controls.Add(New LiteralControl("<div class='newRow'>"))
text = "<div class='fileName'>" & name & "</div>"
container.Controls.Add(New LiteralControl(text))
text = "<div class='fileType'>" & type & "</div>"
container.Controls.Add(New LiteralControl(text))
text = "<div class='fileSize'>" & size.ToString() & "kb</div>"
container.Controls.Add(New LiteralControl(text))
container.Controls.Add(New LiteralControl("<div class='fileDownload'>"))
Dim newBtn As New Button
newBtn.ID = "link" & id
newBtn.Text = "Download"
newBtn.CssClass = "newbie"
AddHandler newBtn.Click, AddressOf Retreive_Doc
newBtn.CommandArgument = id
container.Controls.Add(newBtn)
container.Controls.Add(New LiteralControl("</div>"))
container.Controls.Add(New LiteralControl("<div class='fileDelete'>"))
Dim newDelBtn As New Button
newDelBtn.ID = "delete" & id
newDelBtn.Text = "Delete"
newDelBtn.CssClass = "delBtn"
AddHandler newDelBtn.Click, AddressOf Retreive_Xls
newDelBtn.CommandArgument = id
container.Controls.Add(newDelBtn)
container.Controls.Add(New LiteralControl("</div>"))
container.Controls.Add(New LiteralControl("</div>"))
Loop
End If
Catch ex As Exception
MsgBox(ex.ToString())
Finally
myConnection.Close()
End Try
End Sub
Protected Sub Retreive_Doc(ByVal sender As Object, ByVal e As System.EventArgs) Handles LinkButton1.Click
Dim button As Button = sender
Dim id As Integer = button.CommandArgument
Dim cmd As SqlCommand = New SqlCommand("Uploads_GetFile")
cmd.CommandType = CommandType.StoredProcedure
cmd.Parameters.AddWithValue("#id", id)
Dim dt As DataTable = GetData(cmd)
If dt IsNot Nothing Then
download(dt)
End If
End Sub
I could show the functions called from this function, but the initial function isn't even being called so I'm not sure there is a point.
My HTML is as follows:
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:FileUpload ID="upload1" runat="server" /><asp:Button ID="test1" runat="server" Text="Upload" />
<asp:TextBox ID="folderTag" runat="server" ></asp:TextBox>
<asp:Button ID="search" runat="server" Text="Search" />
<asp:Label ID="folderName" runat="server">General</asp:Label><br />
<div id="navContainer" runat="server">
</div>
<div id="hiddenContent">
<asp:LinkButton ID="LinkButton1" CssClass="hide" runat="server" OnClick = "Retreive_Doc">Download Doc</asp:LinkButton>
<asp:LinkButton ID="LinkButton2" CssClass="hide" runat="server" OnClick = "Retreive_Xls">Download xls</asp:LinkButton>
</div>
<div id="container" runat="server">
</div>
</form>
As I said before. This was working a few days ago and through the course of adding some other functionality somehow I lost it.
I'm unsure of why it posts back without calling any function.
Thanks for any help!

Answer 1

You need to recreate the controls with same ID in post back if you created them dynamically. Otherwise, they will disappear after postback.
Remove If Not IsPostBack Then in page load event.
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
Handles Me.Load
folder = "Main"
PopulateFiles(folder)
End Sub
Another thought:
Is there a reason not to use CommandEvent instead of Click event if you want CommandArgument?
Again, Is there a reason not to use PlaceHolder instead of <div id="container" runat="server">?
AddHandler newBtn.Command, AddressOf Retreive_Doc
newBtn.CommandArgument = id
....
protected void Retreive_Doc(object sender, CommandEventArgs e)