关于c＃：变量未声明或从未分配过警告

The variable is either undeclared or was never assigned warning

我有这样的代码：

这是基类：

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public class BaseClass : UserControl
{
protected ListView list;
protected TreeView tree;

public BaseClass()
{
//...
}
//...
}

子班

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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";
}
}

警告：

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

我做错什么了？这个变量在基类中声明，并在子类中赋值。