ASP.NET - Cargar un modal al pulsar un Button

<asp:scriptmanager id="ScriptManager1" runat="server">

</asp:scriptmanager>

<asp:button id="Button1" runat="server" text="Button" />

<cc1:modalpopupextender id="ModalPopupExtender1" runat="server"

	cancelcontrolid="btnCancel" okcontrolid="btnOkay"

	targetcontrolid="Button1" popupcontrolid="Panel1"

	popupdraghandlecontrolid="PopupHeader" drag="true"

	backgroundcssclass="ModalPopupBG">

</cc1:modalpopupextender>

<asp:panel id="Panel1" style="display: none" runat="server">

	<div class="HellowWorldPopup">

                <div class="PopupHeader" id="PopupHeader">Header</div>

                <div class="PopupBody">

                    <p>This is a simple modal dialog</p>

                </div>

                <div class="Controls">

                    <input id="btnOkay" type="button" value="Done" />

                    <input id="btnCancel" type="button" value="Cancel" />

		</div>

        </div>

</asp:panel>