变量未声明或从未分配警告

我有这样的代码：

这是基类：

public class BaseClass : UserControl { protected ListView list; protected TreeView tree; public BaseClass() { //... } //... } 

儿童class

 public partial class MyClass : BaseClass { public MyClass() { InitializeComponent(); this.BackColor = VisualStyleInformation.TextControlBorder; this.Padding = new Padding(1); } //... } partial class MyClass { //... private void InitializeComponent() { this.tree = new System.Windows.Forms.TreeView(); this.list = new System.Windows.Forms.ListView(); //... this.tree.Location = new System.Drawing.Point(0, 23); this.tree.Name = "blablabla"; } } 

并警告：

 Warning 1 The variable 'tree' is either undeclared or was never assigned. Warning 2 The variable 'list' is either undeclared or was never assigned. 

我究竟做错了什么 ？ 此变量在基类中声明，并在子类中指定。