error: void value not ignored as it ought to be

template <typename Z> Z myTemplate <Z> :: popFromVector ()
{
    if (myVector.empty () == false)
        return myVector.pop_back ();

    return 0;
}

int main ()
{
    myTemplate <int> obj;

    std :: cout << obj.popFromVector();

    return 0;
}

Error:

error: void value not ignored as it ought to be

AFAI can see, the return type of popFromVector is NOT void. What's the point that I am missing? The error disappears when I comment out this call in main().