@mamsds This thread is a decade old. That OP seems to be claiming that instead of m_temperatureLineSeries = new QLineSeries(); you need m_temperatureLineSeries = new QLineSeries(m_temperatureChart );. However I do not believe that is true/will make any difference: m_temperatureChart->addSeries(m_temperatureLineSeries); line does that anyway. I suggest you open your own thread if you have a problem. You will need a minimal, standalone example program which illustrates the issue.