Strange Templates Error

[audinue]

Did I missed something here?

template<typename T>class A {

public:
  template<typename T2> A<T2> toA() {
    return A<T2>();
  }
};

In the main function, this code just works fine:

A<int> a1;
A<float> a2 = a1.toA<float>(); // Works fine! As expected.

I think there is nothing wrong with the code,
but G++ gives me syntax errors:

template<typename T>class B {

  A<T> a;

public:

  B( void ) { ; }
  B( const A<T> &a ) { this->a = a; }

  template<typename T3> B<T3> toB() {
    return B<T3>( a.toA<T3>() ); // error?

    // ???.cpp: In member function `B<T3> B<T>::toB()':
    // ???.cpp:9999: error: expected primary-expression before '(' token
    // ???.cpp:9999: error: expected primary-expression before '>' token
    // ???.cpp:9999: error: expected primary-expression before ')' token
  }
};

I tried to compile it in VC and it gave me a strange error message:

B<int> b;
b.toB<double>(); // x:\somewhere\code.cpp(9999) : error C2062: type 'double' unexpected

And then I tried another way:

template<typename T3> B<T3> toB() {
  A<T3> a1 = this->a.toA<T3>(); // won't work

  A<T> a2 = this->a;
  A<T3> a3 = a2.toA<T3>(); // silly, this way won't work too
}

Thank's in advance.

EDIT: Sorry for my English.. T.T