diff --git a/src/Ursa.Themes.Semi/Controls/Timeline.axaml b/src/Ursa.Themes.Semi/Controls/Timeline.axaml
index 40d3b6a..ef7d859 100644
--- a/src/Ursa.Themes.Semi/Controls/Timeline.axaml
+++ b/src/Ursa.Themes.Semi/Controls/Timeline.axaml
@@ -48,7 +48,7 @@
                         Grid.Column="1"
                         RowDefinitions="Auto, *">
                         <ContentPresenter
-                            Name="PART_Icon"
+                            Name="{x:Static u:TimelineItem.PART_Icon}"
                             Grid.Row="0"
                             Margin="8"
                             HorizontalAlignment="Center"
@@ -64,7 +64,7 @@
                             Fill="{DynamicResource TimelineLineBrush}" />
                     </Grid>
                     <ContentPresenter
-                        Name="PART_Header"
+                        Name="{x:Static u:TimelineItem.PART_Header}"
                         Grid.Row="0"
                         Grid.Column="2"
                         Margin="8,4"
@@ -74,7 +74,7 @@
                         FontSize="14"
                         Foreground="{DynamicResource SemiGrey9}" />
                     <ContentPresenter
-                        Name="PART_Content"
+                        Name="{x:Static u:TimelineItem.PART_Content}"
                         Grid.Row="1"
                         Grid.Column="2"
                         Margin="8,2"
@@ -84,7 +84,7 @@
                         TextElement.FontSize="12"
                         TextElement.Foreground="Gray" />
                     <TextBlock
-                        Name="PART_Time"
+                        Name="{x:Static u:TimelineItem.PART_Time}"
                         Grid.Row="0"
                         Grid.Column="0"
                         Margin="8,2"
diff --git a/src/Ursa/Controls/Timeline/TimelineItem.cs b/src/Ursa/Controls/Timeline/TimelineItem.cs
index e40841f..371f6cd 100644
--- a/src/Ursa/Controls/Timeline/TimelineItem.cs
+++ b/src/Ursa/Controls/Timeline/TimelineItem.cs
@@ -138,12 +138,12 @@ public class TimelineItem: HeaderedContentControl
     protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
     {
         base.OnApplyTemplate(e);
-        PseudoClasses.Set(PC_EmptyIcon, Icon is null);
         _headerPresenter = e.NameScope.Find<ContentPresenter>(PART_Header);
         _iconPresenter = e.NameScope.Find<ContentPresenter>(PART_Icon);
         _contentPresenter = e.NameScope.Find<ContentPresenter>(PART_Content);
         _timePresenter = e.NameScope.Find<TextBlock>(PART_Time);
         _rootGrid = e.NameScope.Find<Grid>(PART_RootGrid);
+        PseudoClasses.Set(PC_EmptyIcon, Icon is null);
         SetMode(Mode);
     }
 
@@ -185,6 +185,7 @@ public class TimelineItem: HeaderedContentControl
 
     internal void SetWidth(double? left, double? mid, double? right)
     {
+        if (_rootGrid is null) return;
         _rootGrid.ColumnDefinitions[0].Width = new GridLength(left??0);
         _rootGrid.ColumnDefinitions[1].Width = new GridLength(mid??0);
         _rootGrid.ColumnDefinitions[2].Width = new GridLength(right??0);