... because you are already implicitly referencing the mscorlib.dll assembly that contains this namespace with the registry types. This don't show up in the Reference list, and the reason is all VB projects (must) implicitly reference the Microsoft.VisualBasic.dll assembly, which in turn reference the mscorlib library, the compiler adds these. The former contains the VB Runtime library and the latter the .Net Common Language Runtime library (CLR, at some time called Common Object Runtime), both containing core functionality.ggunter said:You don't actually add a reference.