equal value range on a map

I've got a map declared as:

std::map< std::pair<int, int>, bool > allPositions (essentially, keys are just 2D points).

I need to get the range of its elements whose values are true

Using std::equal_range

auto range = std::equal_range(allPositions.begin(), allPositions.end(), true);

gives these errors

Error C2672 'operator __surrogate_func': no matching overloaded function found xutility

Error C2893 Failed to specialize function template 'unknown-type std::less<void>::operator ()(_Ty1 &&,_Ty2 &&) const' xutility

Error C2056 illegal expression xutility

Error C2672 'operator __surrogate_func': no matching overloaded function found algorithm

Error C2893 Failed to specialize function template 'unknown-type std::less<void>::operator ()(_Ty1 &&,_Ty2 &&) const' algorithm

I think I don't need predicate function here because std::pair has got overloaded operator < - otherwise map code wouldn't have been compiled

So how to use std::equal_range for map to get range of equal values ?