Incomplete Class using templates in C++

Question

SOLVED: See answer on the bottom

I'm rather new to C++ so this might be a stupid question, but I am trying to write a template class for vectors using the built in STL vectors. It is an assignment from the University. I created a Header file and a cpp-source file, so I can define the class Vector in the Header and declare it's functions in the source file. I get the following errors:

Vector.cpp:27:59: error: invalid use of incomplete type ‘class Vector<T, n>’
Vector<T, n>& Vector<T, n>::operator=(const Vector<U,n>& v){
                                                           ^
In file included from Vector.cpp:1:0:
Vector.h:5:7: note: declaration of ‘class Vector<T, n>’
 class Vector {
       ^~~~~~
Vector.cpp:42:59: error: invalid use of incomplete type ‘class Vector<T, n>’
 Vector<T, n>& Vector<T, n>::operator+(const Vector<U,n>& v){
                                                           ^
In file included from Vector.cpp:1:0:
Vector.h:5:7: note: declaration of ‘class Vector<T, n>’
 class Vector {
       ^~~~~~

My code is this:

Header file (Vector.h):

#include <vector>
using namespace std;

template <class T, int n>
class Vector {
public:
    Vector();
    Vector(int);
    Vector(const Vector<T, n>&);

    ~Vector();

    template<class U>
    Vector<T, n> operator=(const Vector<U, n>&);

    T& operator[](int i);

    template<class U>
    Vector<T, n> operator+(const Vector<U, n>&);
    template<class U>
    Vector<T, n> operator-(const Vector<U, n>&);
    template<class U>
    T operator*(const Vector<U, n>&);

    template<class S>
    Vector<T, n> operator*(const S&);

  /*  template<class S>
    friend Vector<T, n> operator*(const S&, Vector<T, n>&);*/

    template<class F>
    Vector<T, n> apply_Funktor();

private:
    vector<T> values;
    const int size;
};
/*
template<class S, class T, int n>
Vector<T, n> operator*(const S& s, const Vector<T, n> v){
    return v * s;
};*/

And the source-cpp file:

#include "Vector.h"
#include <vector>
using namespace std;

template <class T, int n>
Vector<T, n>::Vector(): size(n){
    vector<T> values;
}

template <class T, int n>
Vector<T, n>::Vector(int v): size(n){
    vector<T> values;
    values.assign(v, n);
}

template <class T, int n>
Vector<T, n>::Vector(const Vector<T, n>& v): size(v.size){
    values = v.values;
}

template <class T, int n>
Vector<T, n>::~Vector(){
    delete values;
}

template<class U, class T, int n>
Vector<T, n>& Vector<T, n>::operator=(const Vector<U,n>& v){
    delete values;
    vector<T> values;
    for(int i = 0; i < size; i++){
        values.push_back((T) v.values[i]);
    }
    return *this;
}

template<class T, int n>
T& Vector<T, n>::operator[](int i){
    return values[i];
}

template<class U, class T, int n>
Vector<T, n>& Vector<T, n>::operator+(const Vector<U,n>& v){
//more Code to come but I already get the error here
}

The error occurs when I try to build my project with NetBeans. I dont have a main yet to use the Vector. I already searched the internet for solutions but I didnt come across anything helpful. I learned about forward declaration but it seems to me that this isnt the case here, because Im including the header file.

Thank you for your help :)

!!!EDIT / SOLUTION: My tutor in class solved it: The problem is that instead of doing

template<class U, class T, int n>

I have to put it like this:

template<class T, int n>
template<class U>