namespace error

[tuzojazz]

Hi

I'm writing an activex and I want to include the namespaces "System" and "Microsoft::Win32" into my control window class .cpp file.

I'm writing these lines:

using namespace System;
using namespace Microsoft::Win32;


When I compile I get these errors

error C2871:'System': does not exist or is not a namespace
error C2653:'Microsoft':is not a class or namespace name
error C2871:'Win32': does not exist or is not a namespace

What could be wrong?
What can I do?

Thanks!!