diff --git a/Elwig/Windows/DeliveryAdminWindow.xaml.cs b/Elwig/Windows/DeliveryAdminWindow.xaml.cs
index edbb90f..f4ea414 100644
--- a/Elwig/Windows/DeliveryAdminWindow.xaml.cs
+++ b/Elwig/Windows/DeliveryAdminWindow.xaml.cs
@@ -1309,8 +1309,7 @@ namespace Elwig.Windows {
 
         private void ModifiersInput_SelectionChanged(object sender, SelectionChangedEventArgs evt) {
             if (!IsEditing && !IsCreating) return;
-            var mod = ModifiersInput.SelectedItems.Cast<Modifier>();
-            var source = ModifiersInput.ItemsSource.Cast<Modifier>();
+            var mod = ModifiersInput.SelectedItems.Cast<Modifier>().ToList();
             if (App.Client.IsMatzen) {
                 var kl = mod.Where(m => m.Name.StartsWith("Klasse "));
                 if (kl.Count() > 1) {
@@ -1330,8 +1329,8 @@ namespace Elwig.Windows {
 
         private void LesewagenInput_Changed(object sender, RoutedEventArgs evt) {
             if (!IsEditing && !IsCreating) return;
-            var mod = ModifiersInput.SelectedItems.Cast<Modifier>();
-            var source = ModifiersInput.ItemsSource.Cast<Modifier>();
+            var mod = ModifiersInput.SelectedItems.Cast<Modifier>().ToList();
+            var source = ModifiersInput.ItemsSource.Cast<Modifier>().ToList();
             var lw = LesewagenInput.IsChecked == true;
             if (App.Client.IsMatzen) {
                 var kl = mod.Where(m => m.Name.StartsWith("Klasse ")).Select(m => m.ModId).LastOrDefault("A")[0];