Operator overloading and copy constructor. Can't find the error.

    A simple program with operator overloading and copy constructor:
#include <iostream>
#include <string>
using namespace std;

class Vector {
    private:
        float x,y;
    public:
        Vector(float u, float v);
        Vector(void);
        Vector operator+ (Vector a);
        Vector(Vector &source);
        void Show(void);
};
void Vector::Show(void) {
    cout <<"(" << x <<"," <<y <<")";
}
Vector::Vector(float u, float v) {
    x=u; y=v;
}
Vector::Vector(void) {
    x=0; y=0;
}
Vector::Vector(Vector &source) {
    x = (source.x)*2 ; y = (source.y)*2 ;
}
Vector Vector::operator+ (Vector a) {
    Vector temp;
    temp.x = x + a.x;
    temp.y = y + a.y;
    return temp;
}

int main(void) {
    Vector a(3,1), b(5,2), c, d;
    c = a+b;
    d = a.operator+ (b);
    cout << "Data members of the vector c: ";
    c.Show();
    Vector e(a+b);
    cout <<endl << "Data members of the vector e: ";
    e.Show();

    return 0;
}

    The compiler (g++ -pedantic -W -Wall) says:
teste.cpp: In function `int main()':
teste.cpp:36: error: no matching function for call to
`Vector::Vector(Vector)'
teste.cpp:24: note: candidates are: Vector::Vector(Vector&)
teste.cpp:37: error: no matching function for call to
`Vector::Vector(Vector)'
teste.cpp:24: note: candidates are: Vector::Vector(Vector&)
teste.cpp:40: error: no matching function for call to
`Vector::Vector(Vector)'
teste.cpp:24: note: candidates are: Vector::Vector(Vector&)
teste.cpp:21: note: Vector::Vector()
teste.cpp:18: note: Vector::Vector(float, float)

Without the copy constructor Vector::Vector(Vector &source) , it works
fine.

Would anyone know what is wrong in the code?
Thanks in advance.