[NullReferenceException: Object reference not set to an instance of an object.]
Imazen.Crop.CropImage.AddFileReferences() in     C:UsersAdministratorDocumentsWebCropImageWebCropImageCropImage.cs:409
Imazen.Crop.CropImage.CreateChildControls() in C:UsersAdministratorDocumentsWebCropImageWebCropImageCropImage.cs:191
System.Web.UI.Control.EnsureChildControls() +188
System.Web.UI.Control.PreRenderRecursiveInternal() +59
System.Web.UI.Control.PreRenderRecursiveInternal() +221
System.Web.UI.Control.PreRenderRecursiveInternal() +221
System.Web.UI.Control.PreRenderRecursiveInternal() +221
System.Web.UI.Control.PreRenderRecursiveInternal() +221
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4296

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="default.aspx.cs" Inherits="gallery_crop_default" MasterPageFile="~/app_assets/ajax.master" %>

<%@ Register Assembly="Imazen.Crop" Namespace="Imazen.Crop" TagPrefix="ic" %>

 <asp:Content ID="content_head" runat="server" ContentPlaceHolderID="cph_main_head_1"></asp:Content>
 <asp:Content ID="content_body" runat="server" ContentPlaceHolderID="cph_main_body_1">

<form id="form1" runat="server">

    <h3>Last crop results:</h3>
    <div>
        <asp:Image ID="result" runat="server" Visible="false" />
    </div>

    <h3>Basic example</h3>

    <asp:Image ID="Image1" runat="server" ImageUrl="images/328.jpg" />
    <br />

    <ic:CropImage ID="CropImage1" runat="server" Image="Image1" CanvasWidth="300" />

    <asp:Button ID="Button1" runat="server" Text="Crop" OnClick="btn_crop_Click" />
</form>

protected void btn_crop_Click(object sender, EventArgs e)
{
    //We're assuming the default names are used here - Button1, Image1, CropImage1, Button2, Image2, CropImage2, etc.
    //Find the cropimage instance near the clicked button
    CropImage ci = this.FindControl(((Button)sender).ID.Replace("Button", "CropImage")) as CropImage;


    //Show the image using the CroppedUrl property
    result.ImageUrl = ci.CroppedUrl;
    result.Visible = true;

    //Save an unneccesary copy of the file out with Crop(), just to show we can
    ci.Crop(MapPath("~/images/last-cropped"), true);

}