I have received the following .NET error several times in the past when developing nested databound controls. I have found the solution does not have good coverage on the Internet. The curious thing about this error is that it does not appear until 2nd or 3rd postback on the page.
[box]The SqlDataSource control does not have a naming container. Ensure that the control is added to the page before calling DataBind[/box]
The cause is simple, however. It occurs when you use a ControlParameter on a DataSource that is within another data control. I ran into it again today on a Gridview within a DataList for example. The error occurs because the inner control cannot find the control containing the parameter for some reason.
The solution is simple as well. You must remove the ControlParameter from the DataSource that is inside the other control. This can be accomplished by using a normal <asp:Parameter> and assigning a DefaultValue to it when the outer control binds.