C++ template class inherits from template class, cannot access member variable

Question

I try to make a class template where a parameterized class Child inherits from a parameterized class Base. The derived class cannot access the members in the base class though.

template <typename T>
class Base
{
protected:
  T _value;
};

template <typename T>
class Child: Base<T>
{
public:
  T accessValue()
  {
    return _value;
  }
};

This gives the following error message:

main.cpp: In member function 'T Child::accessValue()': main.cpp:21: error: '_value' was not declared in this scope

It works if I change the declaration to:

template <typename T>
class Child: Base<int>

but that obviously defies the purpose of the whole template thing.

I Think this must be something really basic but I could not find a solution neither on this site nor anywhere else. Can someone please help me? Thanks in advance!