QAbstractListModel Cannot call my method in qml

[Mihaill]

Hi.
I have inherited class

class MarkerModel : public QAbstractListModel
{
    Q_OBJECT

And I create my method

public slots:
    void addMarker(const QGeoCoordinate &coordinate);

I register type in main.cpp

qmlRegisterType<MarkerModel>("MarkerModel", 1,0, "MarkerModel");

In qml I am passing a pointer to this class.
And I want use all methods: 'rowCount', 'addMarker' and else in qml, but I get error:

Cannot call methods  'addMarker' of null

How I can fix this?