C sharp - Generar un postback en un ItemDataBound de un repeater c# .net

protected void repItem_ItemDataBound(object sender, RepeaterItemEventArgs e,)

{

    DropDownList ddl = (DropDownList)e.Item.FindControl("dddiag");

    Label llbel = (Label)e.Item.FindControl("lbeje");

    if (ddl.SelectedValue == "2") { Label1.Text = "funca"; }

}

<asp:DataList runat="server" id="list1" OnItemCommand="list1_ItemCommand">

        <ItemTemplate>

                 <asp:LinkButton runat="server" id="link1" CommandName="show" CommandArgument="Hola"></asp:LinkButton>

        </ItemTemplate>

<asp:DataList>

//en c#

void list1_ItemCommand(Object sender, DataGridCommandEventArgs e)

{

    if(((LinkButton)e.CommandSource).CommandName=="show")

    {

        Label1.Text = "funca";

    }

}