Hello, What I am doing: I am taking the Microsoft Enterprise Library 4.1 and attempting to expand upon it using a few derived classes. I have created a MyLogEntry, MyFormatter, and MyTraceListener which derive from their respective base classes when you remove the "My" from their names. What my problem is: Everything compiles fine. When I go to run a test using Logger.Write(logEntry) it errors right after it initializes MyTraceListener with an error message: "The current build operation (... EnterpriseLibrary.Logging.LogWriter, null]) failed: Constructor on type 'MyLogging.MyFormatter' not found. (Strategy type ConfiguredObjectStrategy, index 2) I figured it was something to do with the constructor so I tried removing it, add it, and adding a call to the base class LogFormatter. Nothing has worked. Does anyone have insight into this problem? Is it maybe a reference issue? Bad App.config configuration? Thank you in advance