If your application services aren't built on standard technologies, they may not be recognized out-of-the box. You can monitor these technologies, but you'll need to define them as custom services with specific service entry points. Dynatrace allows you to define any method, class, or interface as the entry point of a service to be monitored.
You can define custom services for Java, .NET, and PHP. See How do I configure custom services? to learn how.