C++ signal and custom type variable use in QML

[penguin_chris]

I have created a custom type inheriting from QObject.
I have declared the type with Q_DECLARE_METATYPE() with qmlDeclareType() and also with qRegisterMetaType().

From another object declared as a component in QML I emit a signal which has the type as a parameter now when the signal is handled from the QML I cannot access any of the properties of the type.
In debug output while debugging

Error: Cannot assign [undefined] to QString
is shown whenever I try to access any property of the variable and

Error: <variableName> is not defined
is shown.

my signal is declared as follows:

signals:
    void readTagBCard(const BCard& tagc);

and handled in qml as follows:

onReadTagBCard:{            
            txtFullName.text = tagc.lastName;
        }

the method is lastName is declared as follows:

QString lastName() const {return mlastName;};

How can I access methods on custom type variables in QML?