how to define my allocator

hi!
   i want to define my allocator in my allocator, so i can make a
memory pool for my stl vector list .....

code like this

#include <vector>
#include <list>

#include <iostream>

template <typename T>
class gs_allocator //: public allocator<T>
{
public:
    typedef T value_type;
    typedef value_type* pointer;
    typedef const value_type* const_pointer;
    typedef value_type& reference;
    typedef const value_type& const_reference;
    typedef std::size_t size_type;
    typedef std::ptrdiff_t difference_type;

    gs_allocator() {}
    gs_allocator(const gs_allocator&) {}
    ~gs_allocator() {}

    // rebind the class type u
    template <class u>
    struct rebind{
        typedef gs_allocator<u> other;
    };

    pointer address(reference x) const { return &x; }
    const_pointer address(const_reference x) const
    {
        return &x;
    }

    pointer allocate(size_type n, const_pointer = 0)
    {
        void* p = std::malloc(n * sizeof(T));
        if (!p)
            throw std::bad_alloc();

        return static_cast<pointer>(p);
    }

    void deallocate(pointer p, size_type)
    {
        std::free(p);
    }

    size_type max_size() const
    {
        return static_cast<size_type>(-1) / sizeof(value_type);
        //return size_type(UNIT_MAX/sizeof(T));
    }

    void construct(pointer p, const value_type& x)
    {
        new(p) value_type(x);
    }

    void destroy(pointer p) { p->~value_type(); }

private:
    void operator = (const gs_allocator&);
};

template<typename _T1, typename _T2>
inline bool operator == (const gs_allocator<_T1>&, const
gs_allocator<_T2>&)
{
    return true;
}

template<typename _T1, typename _T2>
inline bool operator != (const gs_allocator<_T1>&, const
gs_allocator<_T2>&)
{
    return false;
}

int main()
{
    typedef std::list<int, gs_allocator<int> >gslist;
    gslist mylist;
    mylist.push_back(1);
    mylist.push_back(1);
    mylist.push_back(1);

    return 0;
}

vc 2005

Error 1 error C2664: 'gs_allocator<T>::gs_allocator(const
gs_allocator<T> &)' : cannot convert parameter 1 from
'gs_allocator<T>' to 'const gs_allocator<T> &' c:\program files
\microsoft visual studio 9.0\vc\include\list 67

i had defined gs_allocator(const gs_allocator&) {} , so what's
wrong?