Changing the font size of the title of a LineChartModel graphic

I need to change the font size of the chart title, so far I have this:

<script type="text/javascript">
            function alterarLegend() {
                this.cfg.highlighter = {
                    tooltipAxes : 'y'
                };

                this.cfg.axes.yaxis.tickOptions = {
                    textColor : '#000000',
                    formatString : "%.0f"
                };
                this.cfg.axes.yaxis.labelOptions = {
                        textColor : '#000000',
                        fontSize : '150%'
                };

                this.cfg.axes.xaxis.labelOptions = {
                    textColor : '#000000',
                };
                this.cfg.legend = {               
                    show : false,
                    show : true,
                    border : '1px solid black',
                    location : 'ne',
                    fontSize: '150%',
                    renderer : $.jqplot.EnhancedLegendRenderer
                }
            }

        </script>

I've tried something like this:

this.cfg.title = {
    fonstSize: '150%'
}

but the title just disappears.