diff --git a/TimeScheduler/TimeScheduler/Common/NotifyableObject.cs b/TimeScheduler/TimeScheduler/Common/NotifyableObject.cs
index 20a673f..3cfe8e3 100644
--- a/TimeScheduler/TimeScheduler/Common/NotifyableObject.cs
+++ b/TimeScheduler/TimeScheduler/Common/NotifyableObject.cs
@@ -5,7 +5,7 @@ using System.Runtime.CompilerServices;
 namespace TimeScheduler.Common
 {
   /// <summary>Basis-Klasse für Objekte, die sich der Oberfläche mitteilen möchten</summary>
-  abstract class NotifyableObject : INotifyPropertyChanged
+  public abstract class NotifyableObject : INotifyPropertyChanged
   {
     /// <summary>Setzt den neuen Wert auf das Feld, wenn sie unterschiedlich sind und wird das <see cref="PropertyChanged"/>-Ereignis</summary>
     /// <typeparam name="T">Typ des Feldes</typeparam>
diff --git a/TimeScheduler/TimeScheduler/Domain/Impl/FileDomain.cs b/TimeScheduler/TimeScheduler/Domain/Impl/FileDomain.cs
index 4139e68..d3bf89f 100644
--- a/TimeScheduler/TimeScheduler/Domain/Impl/FileDomain.cs
+++ b/TimeScheduler/TimeScheduler/Domain/Impl/FileDomain.cs
@@ -4,13 +4,15 @@ using System.IO;
 using System.Runtime.Serialization.Formatters.Binary;
 using System.Xml.Serialization;
 using System.Linq;
+using System.Reflection;
+
 
 namespace TimeScheduler.Model.Impl
 {
   class FileDomain : IDomain
   {
     #region Konstruktion
-    private List<ITimeItem> allItems_ = new List<ITimeItem>();
+    private List<TimeItem> allItems_ = new List<TimeItem>();
     private string filename_ = string.Empty;
 
     public FileDomain()
@@ -19,11 +21,11 @@ namespace TimeScheduler.Model.Impl
       filename_ = Path.Combine(fi.DirectoryName, fi.Name + ".xmldata");
 
       if (File.Exists(filename_))
-        ReadList(filename_);
+        Load();
       else
       {
         // Wenn nichts vorhanden, dann einen Spielsatz anlegen
-        allItems_ = new List<ITimeItem> {
+        allItems_ = new List<TimeItem> {
           new TimeItem { Description = "Desc 01", From = DateTime.Now.Subtract(TimeSpan.FromHours(2)), Till = DateTime.Now, CostUnit = 14, ItemType = TimeItemType.Normal },
           new TimeItem { Description = "Desc 02", From = DateTime.Now.Subtract(TimeSpan.FromHours(2)), Till = DateTime.Now, CostUnit = 13, ItemType = TimeItemType.Break },
           new TimeItem { Description = "Desc 03", From = DateTime.Now.Subtract(TimeSpan.FromHours(2)), Till = DateTime.Now, CostUnit = 12, ItemType = TimeItemType.Holiday },
@@ -37,32 +39,40 @@ namespace TimeScheduler.Model.Impl
     #region Hilfsfunktionen
     private void ReadList(string filePath)
     {
-      var xs = new XmlSerializer(typeof(List<ITimeItem>));
       var bin = new BinaryFormatter();
-      using (var rd = new StreamReader(filePath))
-      {
-        var elems = xs.Deserialize(rd) as List<ITimeItem>;
-        allItems_ = elems;
-        //allItems.Clear();
-        //foreach (var elem in elems)
-        //  allItems.Add(elem);
-      }
+      using (var rd = new FileStream(filePath, FileMode.Open))
+        allItems_ = bin.Deserialize(rd) as List<TimeItem>;
     }
 
     private void WriteList(string path)
     {
-      XmlSerializer xs = new XmlSerializer(typeof(List<TimeItem>));
       var bin = new BinaryFormatter();
+      using (var wr = new FileStream(path, FileMode.OpenOrCreate))
+        bin.Serialize(wr, allItems_);
+    }
+
+    private void ReadListXml(string filePath)
+    {
+      var xs = new XmlSerializer(typeof(List<TimeItem>));
+      using (var rd = new StreamReader(filePath))
+        allItems_ = xs.Deserialize(rd) as List<TimeItem>;
+    }
+    private void WriteListXml(string path)
+    {
+      var xs = new XmlSerializer(typeof(List<TimeItem>));
       using (StreamWriter wr = new StreamWriter(path))
-      {
-        xs.Serialize(wr, (List<ITimeItem>)allItems_);
-      }
+        xs.Serialize(wr, allItems_);
+    }
+
+    private void Load()
+    {
+      ReadListXml(filename_);
     }
 
     private void Save()
     {
       var newFilename = filename_ + ".new";
-      WriteList(newFilename);
+      WriteListXml(newFilename);
       File.Delete(filename_);
       File.Move(newFilename, filename_);
     }
@@ -72,7 +82,7 @@ namespace TimeScheduler.Model.Impl
     public List<ITimeItem> GetItems(DateTime date)
     {
       var founded = allItems_.Where(x => x.From.Date == date);
-      return founded.ToList();
+      return founded.Cast<ITimeItem>().ToList();
     }
 
     public Dictionary<int, string> GetCostUnits()
@@ -91,18 +101,18 @@ namespace TimeScheduler.Model.Impl
 
     public void ElementAdded(ITimeItem timeItem)
     {
-      allItems_.Add(timeItem);
+      allItems_.Add((TimeItem)timeItem);
       Save();
     }
     public void ElementChanged(ITimeItem timeItem)
     {
-      allItems_.Remove(timeItem);
-      allItems_.Add(timeItem);
+      allItems_.Remove((TimeItem)timeItem);
+      allItems_.Add((TimeItem)timeItem);
       Save();
     }
     public void ElementRemoved(ITimeItem timeItem)
     {
-      allItems_.Remove(timeItem);
+      allItems_.Remove((TimeItem)timeItem);
       Save();
     }
     #endregion
diff --git a/TimeScheduler/TimeScheduler/Domain/Impl/TimeItem.cs b/TimeScheduler/TimeScheduler/Domain/Impl/TimeItem.cs
index 634cfb2..55effe6 100644
--- a/TimeScheduler/TimeScheduler/Domain/Impl/TimeItem.cs
+++ b/TimeScheduler/TimeScheduler/Domain/Impl/TimeItem.cs
@@ -1,10 +1,33 @@
 using System;
+using System.Runtime.Serialization;
 using TimeScheduler.Common;
 
 namespace TimeScheduler.Model.Impl
 {
-  public class TimeItem : NotifyableObject, ITimeItem
+  /// <summary>
+  /// 
+  /// </summary>
+  /// <remarks>
+  /// <see cref="ISerializable"/> muss implementiert werden, damit die Daten über den BinarFormater serialisiert werden können.
+  /// Für den XmlSerializer müsste die Klasse auf Public gestellt werden, was nicht immer gewünscht ist
+  /// </remarks>
+  [Serializable]
+  public class TimeItem : NotifyableObject, ITimeItem//, ISerializable
   {
+    public TimeItem() { }
+
+    //#region ISerializable
+    //public TimeItem(SerializationInfo info, StreamingContext context)
+    //{
+    //  Description = (string)info.GetValue("Description", typeof(string));
+    //}
+    //public void GetObjectData(SerializationInfo info, StreamingContext context)
+    //{
+    //  info.AddValue("Description", Description, typeof(string));
+    //}
+    //#endregion
+
+    #region ITimeItem
     private string description_;
     public string Description { get { return description_; } set { SetField(ref description_, value); } }
 
@@ -19,5 +42,6 @@ namespace TimeScheduler.Model.Impl
 
     private TimeItemType itemType_;
     public TimeItemType ItemType { get { return itemType_; } set { SetField(ref itemType_, value); } }
+    #endregion
   }
 }
diff --git a/TimeScheduler/TimeScheduler/Model/ATimeItem.cs b/TimeScheduler/TimeScheduler/Model/ATimeItem.cs
deleted file mode 100644
index 953de83..0000000
--- a/TimeScheduler/TimeScheduler/Model/ATimeItem.cs
+++ /dev/null
@@ -1,13 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using TimeScheduler.Common;
-
-namespace TimeScheduler.Model
-{
-  abstract class ATimeItem : NotifyableObject, ITimeItem
-  {
-  }
-}
diff --git a/TimeScheduler/TimeScheduler/TimeScheduler.csproj b/TimeScheduler/TimeScheduler/TimeScheduler.csproj
index 8b16cd0..072d782 100644
--- a/TimeScheduler/TimeScheduler/TimeScheduler.csproj
+++ b/TimeScheduler/TimeScheduler/TimeScheduler.csproj
@@ -61,7 +61,6 @@
     <Compile Include="Domain\Impl\FileDomain.cs" />
     <Compile Include="Domain\Impl\TimeItem.cs" />
     <Compile Include="Domain\TimeItemType.cs" />
-    <Compile Include="Model\ATimeItem.cs" />
     <Compile Include="Model\ITimeItem.cs" />
     <Compile Include="ViewModel\MainViewModel.cs" />
     <Page Include="MainWindow.xaml">