Type a must implement the inherited pure virtual method b

I need a simulated interface steroid in C ++ using an abstract class. But in the Eclipse IDE I get "Several markers on this line - Type" Handler "must implement the inherited pure virtual method 'Handler :: setNext'"

My question is: why is this?

Handler.h

class Handler {
 public:

    virtual void setNext(Handler &next)  = 0;
    Handler();
    virtual ~Handler();
    virtual void process()  = 0;
 public:

    Handler *nextInChain;

};

Handler.cpp

#include "Handler.h"
Handler::Handler(){
}
Handler::~Handler(){
}

Oracle.h

#include "Handler.h"
class Oracle : virtual public Handler {
 public:
    Oracle();
    virtual ~Oracle();
    virtual void process();
    virtual void setNext(Handler &next);
 private:

};

Oracle.cpp

#include "Oracle.h"

Oracle::Oracle(){
Handler AQUI;//AQUI I get Multiple markers at this line
             //- The type 'Handler' must implement the inherited pure virtual method 
 //'Handler::setNext'
}

Oracle::~Oracle(){
}

void Oracle::process(){
}

void Oracle::setNext(Handler &next){
}