Asp:Button控件onclick事件无刷新页面提示消息

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always">
<ContentTemplate>
<asp:Button runat="server" ID="btn_subm" class="button green" Text="保 存" OnClientClick="if(!CheckForm()) return false" OnClick="btn_subm_Click" meta:resourcekey="btn_submResource1" />
</ContentTemplate>
</asp:UpdatePanel>

btn_subm_Click事件代码中如果直接用“p.ClientScript.RegisterStartupScript(typeof(string), scriptKey, “AddSaveSucc()”, true);”会刷新页面，如果用ScriptManager.RegisterStartupScript(this.UpdatePanel1, UpdatePanel1.GetType(), "", "AddSaveSucc()", true);则不会刷新页面弹框