Ajax Tookit Tab Control

I am all excited to get going with AJAX,

I drag the Tab Container onto the page, the I try to drag the Tab Panel on to the page into the Container and can't do it. OK. change to code view Drag the Panel into the container; that works; add header text; render the page and I see a tab. Still pretty happy.

Now I try to drag a Gridview control into the Panel in code view, run the page get an error

Parser Error Message:Type 'AjaxControlToolkit.TabPanel' does not have a public property named 'GridView'.

Not happy!!

Move on, there was a Button in the demo, so lets try and drag that into the control. No! Error again

Parser Error Message:Type 'AjaxControlToolkit.TabPanel' does not have a public property named 'Button'.

O.K. how about a text box

Parser Error Message:Type 'AjaxControlToolkit.TabPanel' does not have a public property named 'TextBox'.

The Demos make this look very simple, So can anyone comment on why this is happening?

this is how a tabcontainer looks like

<ajaxToolkit:TabContainer ID="tabs" runat="server">
<ajaxToolkit:TabPanel ID="Panel1" runat="server">
<ContentTemplate>
<asp:Button ID="Button1" Text="Hit & Run" OnClick="DoSomething" runat="server" />
</ContentTemplate>
</ajaxToolkit:TabPanel>
</ajaxToolkit:TabContainer>

if this doesn't make sense, let see your code ...