Linkbutton command event not work from composite custom control

Hi everyone.

I have maked a composite control which contain a linkbutton control.
protected override RenderControl(HtmlTextWriter writer)
{
...

LinkButton1.RenderControl(writer);

...

}

 
This control will be added in a panel in my page.aspx from code behind.
protected void Page_Load()
{
MyCompositeControl a = new CyCompositeControl();
a.LinkButton1.Command += new CommandEventHandler(LinkButton1_Command);
a.LinkButton1.CommandName= "LinkButton1_Command";
a.LinkButton1.CommandArguments= "abcdefghi";
a.LinkButton1.Text = "Update";

Panel1.controls.add(a);

}

The text and other property, come out correctly in the page,
but the command event doesn't come out, so when i click up the link button,
nothing happen or appear.
 
How is possible?
We have so ...