Vector bullshit

#include <vector>

typedef struct
{
      int a;
} t_struct;


class t_Class
{
      vector <t_struct> v_Vector;
}

It tells me that ISO C++ forbids declaration of 'vector' with no type.  What the hell is the problem here?  I've tried all sorts of different shit but I can't make the fucking vector somehow.

>>1
using namespace std
or the more preferable

      std::vector <t_struct> v_Vector;