SPListItem.Update Fails - sharepoint

Question

Using the following block of code, the listItem.Update fails with a NullReferenceException:
SPWeb web = null;
SPList list = null;
SPListItem listItem = null;
try
{
SPSecurity.RunWithElevatedPrivileges(delegate()
{
using (SPSite site = new SPSite(this.SiteUrl))
{
web = site.OpenWeb();
list = web.Lists[this.ListName];
listItem = list.Items.Add();
listItem["Background"] = "foo";
}
}
);
listItem.Update();
}
catch
{
}
finally
{
web.Dispose();
}
If I move the listItem.Update() method inside of the anonymous delegate, I get "Operation is not valid due to the current state of the object."
Yes, I've combed through SO and have tried many permutations without success.
Any ideas?
Update:
After the first comment, I tried to remove the anonymous delegate from the code to see if it fared any better:
// store the selected item to pass between methods
public T SelectedItem { get; set; }
// set the selected item and call the delegate method
public virtual void Save(T item)
{
SelectedItem = item;
try
{
SPSecurity.RunWithElevatedPrivileges(SaveSelectedItem);
}
catch
{
}
}
public virtual void SaveSelectedItem()
{
if (SelectedItem != null)
{
using (SPSite site = new SPSite(this.SiteUrl))
{
using(SPWeb web = site.OpenWeb())
{
SPList list = web.Lists[this.ListName];
SPListItem listItem = list.Items.Add();
//UpdateListItem(listItem, SelectedItem);
listItem["Background"] = "foo";
listItem.Update();
}
}
}
}
And this still fails "Operation is not valid due to the current state of the object." In both code samples, it looks like site.Impersonating is false. I am using Windows Auth, and Impersonation in the web.config. This is running from the ASP.Net Development server.

Answer 1

I found an example from this site (blackninjasoftware). I create a reference to the site, grab its SystemAccount token and then create another reference to the site, using the admin token. It seemed a little hackish to me at first - but hey - I have a deadline.
Final working method body now looks like:
SPListItem new_item = null;
SPSite initialSite = new SPSite(this.SiteUrl);
using (var site = new SPSite(this.SiteUrl, initialSite.SystemAccount.UserToken))
{
// This code runs under the security context of the SHAREPOINT\system
// for all objects accessed through the "site" reference. Note that it's a
// different reference than SPContext.Current.Site.
using (var elevatedWeb = site.OpenWeb())
{
elevatedWeb.AllowUnsafeUpdates = true;
SPList list = elevatedWeb.Lists[this.ListName];
new_item = list.Items.Add();
UpdateListItem(new_item, item);
if (new_item != null)
{
new_item.Update();
}
}
}
initialSite.Dispose();