NUnit 2.2 issues with Delphi 2005

I tried creating some simple unit tests with NUnit 2.2 that comes with Delphi 2005, but unfortunately I couldn't get NUnit to recognize my C# libraries. The problem was simply that the attribute TestFixture could not be found, though ILDASM properly shows it.

I just created a simple C# library with Visual Studio .NET, and that worked just fine.

I need to investigate more why this happens with Delphi.