[Solved] Background-color in stylesheet not taking effect

[Endless]

I have a Designer UI window called MonitorWindow. Here's a little bit of the monitorwindow.h file:
@
class MonitorWindow : public QWidget
{
Q_OBJECT

public:
explicit MonitorWindow(QWidget *parent = 0);
~MonitorWindow();
Ui::MonitorWindow *ui;
@
Here's part of the constructor from monitorwindow.cpp where I initialize the stylesheet:
@
MonitorWindow::MonitorWindow(QWidget *parent) :
QWidget(parent),
ui(new Ui::MonitorWindow)
{
ui->setupUi(this);
setStyleSheet("QWidget { background-color: #FF0000; }");
@
When I run the code, the background of the UI form certainly isn't red. Why isn't the background changing to FF0000? A QStackedWidget class is instantiating the MonitorWindow QWidget - will this make a difference?

[dimix]

Try this:
@ setAttribute(Qt::WA_StyledBackground, true);
setStyleSheet("QWidget { background-color: #FF0000; }");@