Exception in template (Designs\ucn2015\eCom/Productlist/eksempel.cshtml): System.ArgumentNullException: Value cannot be null.
Parameter name: source
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at UCNwebshop.CustomCode.Cart.ProductValidation.ProductEliminator.GetDateFromCategoryField[T](LoopItem product, String fieldSystemName) in d:\Workspaces\UCN\Webshop\Development\FraStandardShop\Src\UCNwebshop\CustomCode\Cart\ProductValidation\ProductEliminator.cs:line 172
   at UCNwebshop.CustomCode.Cart.ProductValidation.ProductEliminator.DeadlineCheck[T](LoopItem product) in d:\Workspaces\UCN\Webshop\Development\FraStandardShop\Src\UCNwebshop\CustomCode\Cart\ProductValidation\ProductEliminator.cs:line 73
   at CompiledRazorTemplates.Dynamic.efcefdad.Execute()
   at RazorEngine.Templating.TemplateBase.RazorEngine.Templating.ITemplate.Run(ExecuteContext context)
   at RazorEngine.Templating.TemplateService.Run(ITemplate template, DynamicViewBag viewBag)
   at RazorEngine.Templating.TemplateService.Parse(String razorTemplate, Object model, DynamicViewBag viewBag, String cacheName)
   at RazorEngine.Razor.Parse[T](String razorTemplate, T model, String cacheName)
   at Dynamicweb.Rendering.Template.Output()
@inherits Dynamicweb.Rendering.RazorTemplateBase<Dynamicweb.Rendering.RazorTemplateModel<Dynamicweb.Rendering.Template>>
@using UCNwebshop.CustomCode.Cart.ProductValidation;

@{
/* These keywords must be included for the data to be fetched by Dynamicweb's lazy loading */
/*

    GetLoop("ProductCategories")
    GetLoop("ProductCategoryFields")
    GetDouble("Ecom:Product.Stock")
*/
}

<h2>@GetString("Ecom:Group.Name")</h2>
<ul id="productlist" class="horizontal">
    @foreach (var product in GetLoop("Products"))
    {
        /* DeadlineCheck() ser efter om produktet m� vises j.f. StartDato og SlutDato defineret p� gruppen */
        if (product.DeadlineCheck())
        {
            <li>
                <h3><a href="@product.GetString("Ecom:Product.Link.Clean")">@product.GetString("Ecom:Product.Name")</a>
                </h3>
                <a href="@product.GetString("Ecom:Product.Link.Clean")">@product.GetString("Ecom:Product.ImageSmall.Default")</a>
                <span class="price">
                @product.GetString("Ecom:Product.Price")
            </span>                
                @* StockCheck() ser efter om der er vare p� lager af den p�g�ldende vare. Den tjekker ikke efter reserverede varer. *@
                @if (!product.StockCheck())
                {
                    <p>Ikke p� lager</p>
                }
                @* RegistrationDeadlineCheck() ser efter om tilmeldingsfristen er overskredet j.f. det der er defineret p� gruppen. *@
                else if (!product.RegistrationDeadlineCheck())
                {
                    <p>Overskredet tilmeldingsfrist</p>
                }
                else
                {
                    <a href="/default.aspx?id=@product.GetString("Ecom:Product:Page.ID")&amp;productid=@product.GetString("Ecom:Product.ID")&amp;cartcmd=add">Tilf�j til kurv</a>
                }



                <span class="shortdescription">@product.GetString("Ecom:Product.ShortDescription")</span>
            </li>
        }
        else
        {
            <li>Produkt er udl�bet og vises ikke (@product.GetString("Ecom:Product.Name"))</li>
        }
    }
</ul>