XML Intellisense will not automatically work for a custom configuration section.
Visual Studio may report warnings on compilation complaining that the attributes of the custom configuration section are not defined. These warnings may be ignored.
If you want XML IntelliSense support for a custom configuration section (or if you just want the ‘schema not found’ warnings to disappear), add the following line to your DotNetConfig.xsd file immediately after the first <xs:schema …> line (which is typically the second line in the DotNetConfig.xsd file).
<xs:include schemaLocation="YOUR_DIRECTORY\namespace.assemblyname.xsd"/>
The DotNetConfig.xsd file can be found in your Visual Studio 8 (or 9) installation directory in the Xml\Schemas subdirectory.