Assembly: System.Web (in system.web.dll)
A site map node of the current site map provider under which the root node and all nodes of the child provider is added.
The Provider property of the parentNode does not reference the current provider.
parentNode is a null reference (Nothing in Visual Basic).
providerName cannot be resolved.
The site map file used by providerName is already in use within the provider hierarchy.
The root node returned by providerName is a null reference (Nothing in Visual Basic).
The root node returned by providerName has a URL or key that is already registered with the parent XmlSiteMapProvider.
The AddProvider method links providerName to the current provider as a child of the current provider. The root node of providerName is added to the hierarchy for the current provider as a child node of parentNode. Because the parent provider calls the BuildSiteMap method on providerName, the exceptions that are described in the BuildSiteMap method might be thrown.