As VS2012’s C++ compiler doesn’t support “true” variadic templates, the new runtime library classes that use variadic templates are implemented using macro magic behind the scenes. In order to get the “variadic” templates to accept more than the default of five parameters, you’ll have to set _VARIADIC_MAX to the desired maximum number of parameters (between five and ten).

For more information, see the “faux variadics” section of this blog post on MSDN.