Reason why this Impersonator code doesn't work?

Hi All -
I'm using C#

I got this code over a year ago from here. It worked then, but when i added it into my new project it doesn't work. The code doesn't error out, i just get "access denied" when i try to update the list.

Thanks

public class Impersonator
      {
 
            public static WindowsIdentity CreateIdentity(string User, string Domain, string Password)
            {
                  // The Windows NT user token.
                  IntPtr tokenHandle = new IntPtr(0);
 
                  const int LOGON32_PROVIDER_DEFAULT = 0;
                  const int LOGON32_LOGON_NETWORK = 3;
 
                  tokenHandle = IntPtr.Zero;
 
                  // Call LogonUser to obtain a handle to an access token.
                  bool returnValue = LogonUser(User, Domain, Password, 
                        LOGON32_LOGON_NETWORK, LOGON32_PROVIDER_DEFAULT,
                        ref tokenHandle);
 
                  if (false == returnValue)
                  {
                        int ret = Marshal.GetLastWin32Error();
                        throw new Exception("LogonUser failed with error code: " +  ret);
                  }
 
                  //System.Diagnostics.Debug.WriteLine("Created user token: " + tokenHandle);
 
                  //The WindowsIdentity class makes a new copy of the token.
                  //It also handles calling CloseHandle for the copy.
                  WindowsIdentity id = new WindowsIdentity(tokenHandle);
                  CloseHandle(tokenHandle);
                  return id;
            }
 
            [DllImport("advapi32.dll", SetLastError=true)]
            private static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
                  int dwLogonType, int dwLogonProvider, ref IntPtr phToken);
 
            [DllImport("kernel32.dll", CharSet=CharSet.Auto)]
            private extern static bool CloseHandle(IntPtr handle);
      }
}
 
protected void btnSaveExit_Click(object sender, EventArgs e)
    {
WindowsImpersonationContext wic = Impersonator.CreateIdentity("Admin User Name", "Domain where Admin resids", "Password").Impersonate();
            SPSite site = SPControl.GetContextSite(Context);
            //site.CatchAccessDeniedException = false;
            SPWeb subSite = site.AllWebs["mysite"];
            subSite.AllowUnsafeUpdates = true;
            SPListCollection allSiteLists = subSite.Lists;
            SPList list = subSite.Lists["mylist"];
            SPListItemCollection listItems = list.Items;
            SPListItem newItem = list.GetItemById(Convert.ToInt32(lblUnique.Text));
            wic.Undo();
            ////
            newItem["ApprovedBy"] = txtApprovedBy.Text;
            newItem["ApprovedDate"] = txtApprovedDate.Text;
            ////
            newItem.Update();

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