During runtime, assemblies must be in the output path of the project or in the GAC for deployment. If your project contains a reference to an object that is not in one of the two locations, the reference must be copied to the appropriate output path.

1. In the Project Manager, right-click an assembly DLL in the References folder.
2. Set the Copy Local option to copy the file to the output directory.
   Note: The IDE maintains the Copy Local
   setting until you change it.