Why is Koening lookup not working here?

Argument dependent lookup says:

For arguments of class type (including union), the set consists of... a) The class itself b)...

Then why can't printX find X?

 #include<iostream>
using namespace std;

class A {
public:
    static const int X = 1;
};

class B {
public:
    static void printX(A a)
    {
        cout << "X is " << X << endl;
    }
};

int main(int argc, char** argv)
{
    A a;
    B::printX(a);
    return 0;
}