下面这段小程序，编译时出现变量未定义怎么解决

Option Explicit
Private WithEvents NewButton As CommandButton

Private Sub NewButton_Click()
    MsgBox ″您选中的是动态增加的按钮!″
    End Sub

Private Sub Command1_Click()


If NewButton Is Nothing Then
NewButton.Move Command1.Left + Command1.Width + 240, Command1.Top
    NewButton.Caption = ″新增的按钮″
    NewButton.Visible = True
    End If
Set NewButton = Controls.Add(″″, ″cmdNew″, Me)

End Sub

Private Sub Command2_Click()


If NewButton Is Nothing Then
    Else
    Controls.Remove NewButton
    Set NewButton = Nothing
    End If

End Sub