Nothing showing up in QScrollArea

Nothing showing up in QScrollArea

I have a nice widget that basically looks like a dialog box with a bunch
of QSliders on it. The number of sliders varies depending on the situation
when the dialog (not an actual QDialog; just a QWidget) is invoked.
Since the varying number of sliders causes the box to be different sizes
at different times, I now want to clean things up a bit by confining the
sliders to a QScrollArea. If I understand things correctly, such a scroll
area would display however many sliders fit within its height, and one
could scroll down to see the rest if there were more.
Anyway, I tried a (somewhat complicated) procedure like this:
In constructor of custom QWidget class (m_variableName = member variable):
CustomScrollBox::CustomScrollBox(QWidget* _parent){
setWindowTitle(...);
...
m_scrollArea = new QScrollArea(this);
m_scrollAreaBox = new QGroupBox(m_scrollArea);
m_layout = new QGridLayout();
m_scrollAreaBox->setLayout(m_layout);
m_scrollArea->setWidget(m_scrollAreaBox);
m_scrollArea->setFixedHeight(250);
m_bottomButton = new QPushButton(this); //probably irrelevant
...
[connect calls, etc.]
}
After the constructor, the real, situation-dependent set-up of sliders
occurs:
void
CustomScrollBox::SetUpWidgets(){
for([however many sliders the situation calls for]){
CustomSlider* s = new CustomSlider(this, label); //just a QWidget
consisting of a
//QSlider and a
QLabel to
//the left of it
..
m_layout->addWidget(s, [grid dimensions as needed]);
}
...
[set text on bottom button, etc., and add it as well]
}
This process causes nothing to show up on the overall dialog, except for
an immobile scroll bar on the left. What, if possible, is the proper order
of initialization steps to make this work? My guess is that I might have
given something the wrong parent or set a layout at the wrong time, but
the rearrganements I've tried so far haven't worked...