"Module not found: Error: Cannot resolve module" for react-router and react

Hi,

Hopefully this is not a total noob question, but;

When I run 'webpack' I keep getting a "Module not found: Error: Cannot resolve module" for 'react-router' and 'react'.

Just for clarity I'm running 'npm install' in the example directory and then running 'webpack' in the same directory.

Would appreciate it if someone could help me out :)

Thanks in advance, Jean