Compilation error: "field 'xxx' has incomplete type"

[fedcer]

Hi, I'm trying to compile a program but one of the headers is giving me an error.
The header:

#include "ui_DAQDialog.h"
#include <QDialog>
#include <QMap>
#include <QTime>
#include "QCard"
 
class DAQDialog: public QDialog, public Ui::DAQDialog {
    Q_OBJECT
 
    public:
       DAQDialog(QWidget *parent = 0, QCard *card0 = 0);
 
       QMap<double, double> data;
 
    private slots:
       void doDAQ();
 
    private:
       QCard *Card;
       QTime timer;
       QTime waiter;
};

#include "ui_DAQDialog.h"
#include <QDialog>
#include <QMap>
#include <QTime>
#include "QCard"

class DAQDialog: public QDialog, public Ui::DAQDialog {
    Q_OBJECT

    public:
       DAQDialog(QWidget *parent = 0, QCard *card0 = 0);

       QMap<double, double> data;

    private slots:
       void doDAQ();

    private:
       QCard *Card;
       QTime timer;
       QTime waiter;
};

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The compilation error:

DAQDialog.h:40: error: field 'data' has incomplete type

DAQDialog.h:40: error: field 'data' has incomplete type

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Thanks,

Fedcer