下拉框在选择后更新列表会出现绑定失败的问题

[HaHa-ZYK]

11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=FontSize; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'FontSize' (type 'Double') 11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=FontFamily; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'FontFamily' (type 'FontFamily') 11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=FontWeight; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'FontWeight' (type 'FontWeight') 11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=Foreground; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'Foreground' (type 'Brush') 11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=Padding; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'Padding' (type 'Thickness') 11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment') 11:08:25:486 System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'ComboBoxItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')