connect returning false

[thru]

I am a very beginner learing by trial and error (well I have read a bit already). I was seeing the most simple example, dirview and I though I'd add some code, an object that would be signaled by the TreeView.

So I created a class derived from QObject with the Q_OBJECT macro and set a connection (code below) but the return value of connect is always false.

What I am missing?
And is there a way to get extended information of the error?

Receiver recv;
bool ok=QObject::connect(&tree,SIGNAL(activated(const QModelIndex &)),&recv,SLOT(selected(const ModelIndex &)));

Receiver recv;
bool ok=QObject::connect(&tree,SIGNAL(activated(const QModelIndex &)),&recv,SLOT(selected(const ModelIndex &)));

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this is the declaration of Receiver class:

class Receiver:public QObject{
Q_OBJECT;
 
 
public slots:
    void selected(QModelIndex &);
 
};

class Receiver:public QObject{
Q_OBJECT;


public slots:
    void selected(QModelIndex &);

};

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