How can I add an invitation dialog to my facebook application (using ASP.Net)

Question

I'm developing a facebook application, using IFrame instead of FBML. I have a main page with a sub-iFrame inside. In the inner iframe (the invitation page) I have:

<%@ Register Assembly="Facebook.Web" Namespace="Facebook.Web.FbmlControls" TagPrefix="cc1" %>
<cc1:Fbml ID="Fbml1" runat="server" Xfbml="True">
    <ContentTemplate>
        <cc1:RequestForm ID="RequestForm1" runat="server" Method="Post" Type="Xfbml" Xfbml="True"
            Invite="True" Content="Invite your friends" Action="." Visible="True">
            <ContentTemplate>
                <cc1:MultiFriendSelector ID="MultiFriendSelector1" runat="server" Rows="3" Xfbml="True"
                    ShowBorder="True" EmailInvite="True" Bypass="Cancel" ActionText="Select Friends you want to invite">
                </cc1:MultiFriendSelector>
            </ContentTemplate>
        </cc1:RequestForm>
    </ContentTemplate>
</cc1:Fbml>

This doesn't work at all and when I view the frame source, I get:

<fb:fbml>

        <fb:request-form type="Xfbml" Content="Invite your friends" action="." method="POST">

                <fb:multi-friend-selector actiontext="Select Friends you want to invite" showborder="true" email_invite="true" rows="3" bypass="cancel"></fb:multi-friend-selector>

    </fb:request-form>

</fb:fbml>

Any ideas and/or suggestions are very appreciated. Thanks for reading anyway