Object reference not set to an instance of an object.

Hej, jeg har siddet super længe og bakset med dette kodeværk, der bare ikke vil virke.

Målet er at lave et forum, koden giver fin mening i sig selv, men min "ForumEntry" vil ikke populate min "Entries", der ellers er en "IList<ForumEntry>"

Thread.aspx.cs

 namespace Forum
 {
     public partial class Thread : System.Web.UI.Page
     {
         private Int32 ThreadIdentifier;
         private IList<ThreadEntry> Entries;
         protected void Page_Load(object sender, EventArgs e)
         {
             this.ThreadIdentifier = Convert.ToInt32(Request.QueryString["ID"]);
 
             populateThread();
             showthreads();
         }
 
         public void populateThread()
         {
             ThreadEntry entry = new ThreadEntry(this.ThreadIdentifier);
             entry.ThreadName = "abe";
             entry.EntryID = 1;
             entry.UserID = 1;
             entry.NickName = "T1MeW4sTeR";
             entry.Text = "Dette er det først indlæg i en ellers lang tråd. :)";
             entry.datetime = "hh";
 
             this.Entries.Add(entry);
         }
 
         public void showthreads()
         {
             foreach(ThreadEntry entry in this.Entries)
             {
                 DivEntries.InnerHtml += "Nickname: " + entry.NickName.ToString();
                 DivEntries.InnerHtml += " Time: " + entry.datetime.ToString();
                 DivEntries.InnerHtml += "<br /><br />" + entry.Text.ToString();
             }
         }
     }
 }

Thread.cs

 namespace Forum
 {
     public abstract class ForumThread
     {
         public Int32 ThreadID;
         public string ThreadName;
     }
 }

ThreadEntry.cs

 namespace Forum
 {
     public class ThreadEntry : ForumThread
     {
         public Int32 EntryID;
         public Int32 UserID;
         public string NickName;
         public string datetime;
         public string Text;
 
         public ThreadEntry(Int32 id)
         {
             this.ThreadID = id;
         }
     }
 }

Er der ikke en, der kan hooke mig up med en lækker løsning?