We use ‘using’ key word to add the namespace in the application, but the system still give us the message that it could not find the specific class.
As usually, we forgot to add the reference in the application.
Note: there are three config file when we release an application – ApplicationName.exe.Config, ApplicationName.vshost.exe.Config and app.Config (which locats in the source code). When we operate the config (read and write), in fact, we operate the ApplicationName.exe.Config.