Deriving from std::vector - what am I doing wrong?

Question

Trying to switch from some custom made classes I built to std classes. Just for a start, I am trying to derive from std::vector.

#include <vector>

template < class DATA_T >
class CArray : public std::vector < DATA_T >
{
public:
    DATA_T* Create (size_t length) {
        reserve (length);
        return data;
    }
};

"reserve": Identifier not found
"data":  Identifier not found

As far as I could see, both are public members of std::vector.

What is my mistake?