std::bind with std::bind in parameter [duplicate]

This question already has an answer here:

• std::bind a bound function 2 answers

When I want to create an std::function for wrapping work(..) member, I had a compilation error that tired me.

sample code :

class C{ 
public:
    C(){
        std::function<void(void) > f = std::bind(&C::work,
                                                 this,
                                                 std::bind(&C::step1, this),
                                                 std::bind(&C::step2, this));
        QList<decltype(f)> lst;
        lst.append(f);
        .....
    }
private:
    void work(std::function<bool()> fn1, std::function<bool()> fn2 ) {
        if (fn1()) {
            QTimer::singleShot(1, fn2);
        }
        else {
            QTimer::singleShot(5, fn1);
        }
    }

    bool step1(){return true;}
    bool step2(){return true;}
};

Compile Error:

main.cpp:49: erreur : conversion from 'std::_Bind_helper<false, void (C::*)(std::function<bool()>, std::function<bool()>), C* const, std::_Bind<std::_Mem_fn<bool (C::*)()>(C*)>, std::_Bind<std::_Mem_fn<bool (C::*)()>(C*)> >::type {aka std::_Bind<std::_Mem_fn<void (C::*)(std::function<bool()>, std::function<bool()>)>(C*, std::_Bind<std::_Mem_fn<bool (C::*)()>(C*)>, std::_Bind<std::_Mem_fn<bool (C::*)()>(C*)>)>}' to non-scalar type 'std::function<void()>' requested
                                              std::bind(&C::step2, this));
                                                                        ^

Thanks in advance /requinham