点击父窗体form1工具栏“运行”按钮，使子窗体form2中的timer1运行： form2.Timer1.Enabled =true 为什么不行？

'Dim NewMDIChild As 绘图
Private Sub Main_Load(sender As Object, e As EventArgs) Handles MyBase.Load
       Dim NewMDIChild As New 绘图
        NewMDIChild.MdiParent = Me
        NewMDIChild.Show()
  End Sub
Private Sub 运行TButton1_Click(sender As Object, e As EventArgs) Handles 运行TButton1.Click
        NewMDIChild.Timer1.Enabled = True
  End Sub
不行？