User Control with Inner Property

Hi!
I have an web user control with the following property:
[PersistenceMode(PersistenceMode.InnerProperty)]
public List<LinkButton> Content
{
get
{
return _Content;
}
}
So I can fill this list property simply in the "source" view:
<Content>
<asp:LinkButton runat="server" Text="Link Button 1" />
<asp:LinkButton runat="server" Text="Link Button 2" />
<asp:LinkButton runat="server" Text="Link Button 3" />
....
</Content> This works great, but when I switch to the "design" view, I get the error "System.Web.UI.UserControl has no public property called Content".
Can anybody help me to solve this problem?
Thanks,
Daniel
...