Tooltip for datagridview in vs2005

[undead142]

I'm using VS2005. I designed a form with a datagridview, after that I add a tooltip control. In form_load :

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
ToolTip1.SetToolTip(DataGridView1, "DataGridView1")
End Sub

But when I runned my form, the tooltip "DataGridView1" didn't appear. Why?