I get this error when trying to use a WebTab and No there is only one Register in the ascx page. Here is the header for my ascx page
<%
Please help with why this would happen?
It seems that you have other class name(s) in the namespaces that you have included that are called Tab. In your code-behind, you can use the fully qualified name of the Tab (namespace + class name) to resolve that, e.g.
Infragistics.WebUI.UltraWebTab.Tab
Other things to check - currently you are refenrecing all Infragistics assemblies from cache - you can check your project references and make sure that CopyLocal is not set to true - this way you will have the same assemblies and /bin and GAC and this might be related to the issues you are having.