error: no matching function for call to ‘to_string(std::basic_string

Even though in a template I can have any type, the function to_string does not work on basic strings:

for example:

std::string str("my string");
my_class(str);

with this functor definition:

template<class valuetype>
void operator()(valuetype value)
{
    ...
    private_string_field = std::to_string(value);

does not work. here is the error:

error: no matching function for call to ‘to_string(std::basic_string&)’

What is the best way to avoid it.

In advance, I request avoid linking to irrelevant questions just because of a few common keywords.