Cannot import my graph

[Stanfillirenfro]

Hello!
I am facing the problem of importing my graph.
In the constructor of my window, I have the following code:

ui->customPlot->saveJpg(graphSName, 520, 520);

ui->customPlot->saveJpg(graphSName, 520, 520);

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This work perfectly, but the image is saved in the same file with my executable.
The idea is to show a path to save the graph.
I have the following code:

void myMainwindow::save()
{
    QString graphSName = QFileDialog::getSaveFileName(this, "Information", "Save", "Picture (*.jpg *.pdf. *png)");
    saveGraph->setText(graphSName);
 
    if(!graphSName.isEmpty())
    {
        saveGraphHere(graphSName);
    }
}
 
void myMainWindow::saveGraphHere(QString &graphSName)
{
    ui->customPlot->saveJpg(graphSName, 520, 520);
}

void myMainwindow::save()
{
    QString graphSName = QFileDialog::getSaveFileName(this, "Information", "Save", "Picture (*.jpg *.pdf. *png)");
    saveGraph->setText(graphSName);
 
    if(!graphSName.isEmpty())
    {
        saveGraphHere(graphSName);
    }
}
 
void myMainWindow::saveGraphHere(QString &graphSName)
{
    ui->customPlot->saveJpg(graphSName, 520, 520);
}

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My connect is in the constructor of my MainWindow and as followed:

connect(saveButton, SIGNAL(clicked()), this, SLOT(save()));

connect(saveButton, SIGNAL(clicked()), this, SLOT(save()));

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The problem is that when I clicked on the saveButton, the program just crashes down.

I would be grateful to any help.

Many thanks in advance!