OnUploadedComplete not firing

Question

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="AjaxToolkit" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
<script type="text/javascript">
function AjaxFileUpload1_ClientUploadComplete(sender, e) {
if (sender._filesInQueue[sender._filesInQueue.length - 1]._isUploaded)
__doPostBack("<%= btnViewGallery.UniqueID %>", "");
// Needed to do a postback to refresh gridview only after all files have been uploaded
}
</script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="CommonHeaderContentPlaceHolder" Runat="Server">
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel id="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:HiddenField ID="hdnId" runat="server" />
<asp:HiddenField ID="hdnType" runat="server" />
<div style="width:100%;">
<div class="lblPageHeader">
Gallery Image Upload
</div>
<div style="width:100%;padding:5px;">
<span class="lblClass" >Gallay Category :</span>
<asp:DropDownList ID="ddlGallaryCategory" runat="server" Width="220px" class="ddlClass" AutoPostBack="true" OnSelectedIndexChanged="fn_loadGallery" ViewStateMode="Enabled">
</asp:DropDownList>
</div>
<div style="width:100%;">
<AjaxToolkit:AjaxFileUpload ID="AjaxFileUpload1" runat="server" IsInFileUploadPostBack="true" mode
OnClientUploadComplete="AjaxFileUpload1_ClientUploadComplete"
OnUploadedComplete ="AjaxFileUpload1_UploadComplete"/>
</div>
<div style="width:100%;">
<asp:DataList ID="dlImages" runat="server" RepeatColumns="0" RepeatDirection="Horizontal" BackColor="White" BorderColor="#999999" BorderStyle="None" BorderWidth="1px" CellPadding="3">
<AlternatingItemStyle BackColor="#DCDCDC" />
<FooterStyle BackColor="#CCCCCC" ForeColor="Black" />
<HeaderStyle BackColor="#000084" Font-Bold="True" ForeColor="White" />
<ItemStyle BackColor="#EEEEEE" ForeColor="Black" />
<ItemTemplate>
<table border="0" style="width:100%;border-bottom-color:#60BAEA;border-top-color:#60BAEA;border-left-color:#60BAEA;border-left-color:#60BAEA;" cellspacing="5">
<tr>
<td align="center" style="padding:5px;width:100%;">
<asp:Image ID="img" runat="server" align="center" BorderStyle="Solid" BorderColor="#e0ddd7" BorderWidth="1" Height="50" ImageUrl='<%# DataBinder.Eval(Container.DataItem, "IMAGE_PATH") %>' />
<br />
<asp:LinkButton ID="RemoveLinkBtn" runat="server" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "IMAGE_ID") %>' OnCommand="RemoveLinkBtn_Command" >Remove</asp:LinkButton>
</td>
</tr>
</table>
</ItemTemplate>
<SelectedItemStyle BackColor="#008A8C" Font-Bold="True" ForeColor="White" />
</asp:DataList>
</div>
</div>
<center><asp:Button ID="btnViewGallery" runat="server" Text="View Gallery" OnClick="btnViewGallery_Click" /> </center>
</ContentTemplate>
</asp:UpdatePanel>
</asp:Content>

Code :

#region Ajax Upload File
protected void AjaxFileUpload1_UploadComplete(object sender, AjaxControlToolkit.AjaxFileUploadEventArgs e)
{
string filePath = string.Empty;
try
{
string strID = Session["selectedid"].ToString();
int compid = Convert.ToInt32(Session["COMPID"]);
filePath = (Server.MapPath("~/fileupload/gallery/") + Guid.NewGuid() + System.IO.Path.GetFileName(e.FileName));
AjaxFileUpload1.SaveAs(filePath);
string strFile = filePath.Substring(filePath.LastIndexOf("\\"));
string strFileName = strFile.Remove(0, 1);
string strFilePath = "~/fileupload/gallery/" + strFileName;
string input = Server.MapPath("fileupload/gallery/") + strFileName;
string thumb = Server.MapPath("fileupload/gallery/thumb/") + strFileName;
string output = Server.MapPath("fileupload/gallery/display/") + strFileName;
// Load image.
System.Drawing.Image image = System.Drawing.Image.FromFile(input);
Size thumbnailSize = GetImageSize(image, 110);
System.Drawing.Image thumbnail = resizeImage(image, thumbnailSize);
thumbnail.Save(thumb);
Size displaySize = GetImageSize(image, 640);
System.Drawing.Image display = resizeImage(image, displaySize);
display.Save(output);
// Compute thumbnail size, Get thumbnail & Save thumbnail.
/*
Size thumbnailSize = GetImageSize(image,110);
System.Drawing.Image thumbnail = image.GetThumbnailImage(thumbnailSize.Width,
thumbnailSize.Height, null, IntPtr.Zero);
thumbnail.Save(thumb);
}
catch (Exception ex)
{
Response.Write(ex.Message.ToString());
}
}
#endregion