I cannot get Qt 6.2.4 to connect a signal with a slot.
attempting to run:

///////////////

Plotrect_Actions::Plotrect_Actions(const QVector<PlotDataRect> &plotdatasets, QWidget *parent):plotdatasets(plotdatasets)
{
    setupUi(this);
    setAttribute(Qt::WA_DeleteOnClose);
    plot=new QCustomPlot(this);
    assert(plot);
    assert(rectplot_box);
    plot->setSizePolicy(QSizePolicy::MinimumExpanding,QSizePolicy::MinimumExpanding);
    rectplot_box->addWidget(static_cast<QWidget *>(plot));

    logx->blockSignals(true);
    logx->setText("logscale X");
    connect(logx,SIGNAL(checkStateChanged(Qt::checkStateChanged)),this,SLOT(linearlogXtoggle(Qt::checkStateChanged)));
    logx->blockSignals(false);
    plot->setMouseTracking(true);
}

////

yields the error:
qt.core.qobject.connect: QObject::connect: No such signal QCheckBox::checkStateChanged(Qt::checkStateChanged)

This has me stumped because apparently QCheckBox does have the signal QCheckBox::checkStateChanged (from the documentation).
Any ideas welcome and thanks in advance.