R – Visual Studio 2008 does not show any “obsolete”-warnings

Duplicate: Why are C# collection-properties not flagged as obsolete when calling properties on them?

I just migrated a .NET 1.1 project to .NET 2.0 using Visual Studio 2008. I know that there are references to obsolete methods in the project.

But Visual Studio does not show "obsolete"-warnings after building. The build succeeds and shows only 3 warnings from members that are assigned a value that is never used. When I remove these members there are no warnings at all.

I NEED THESE "OBSOLETE"-WARNINGS

The Warning level is 4 (maximum), Warnings are enabled.

Just one sample:

protected internal DataConnector()
{
    _connectionString = ConfigurationSettings.AppSettings["ProductConnectionString"];
}

All references that should result in an "obsolete"-warning are to members of classes of the .NET Framework.