Here is another charting solution to try. I played around for awhile with this, but gave up. Just seems to have to many options. I need a better way to set it up.
<?php
$snippetPath = $modx->config['base_path'] . 'assets/snippets/pChart/pChart/';
$fontPath = $modx->config['base_path'] . 'assets/snippets/pChart/Fonts/';
include_once($snippetPath.'pData.class');
include_once($snippetPath.'pChart.class');
$chartWidth= (isset($chartWidth))? $chartWidth : 400;
$chartHeight = (isset($chartHeight))? $chartHeight : 400;
$chartTitle = (isset($chartTitle))? $chartTitle : 'Chart';
// Dataset definition
$DataSet = new pData;
$DataSet->AddPoint(array(0,70,70,0,0,70,70,0,0,70),"Serie1");
$DataSet->AddPoint(array(0.5,2,4.5,8,12.5,18,24.5,32,40.5,50),"Serie2");
// $DataSet->AddPoint(array($chartData1), "Serie1");
$DataSet->AddAllSeries();
// $DataSet->SetAbsciseLabelSerie();
// $DataSet->SetSerieName("January","Serie1");
// $DataSet->SetSerieName("February","Serie2");
// Initialise the graph
$Test = new pChart($chartWidth,$chartHeight);
$Test->setFontProperties($fontPath . "tahoma.ttf",8);
$Test->setGraphArea(50,30,585,200);
$Test->drawFilledRoundedRectangle(7,7,693,223,5,240,240,240);
$Test->drawRoundedRectangle(5,5,695,225,5,230,230,230);
$Test->drawGraphArea(255,255,255,TRUE);
$Test->drawScale($DataSet->GetData(),$DataSet->GetDataDescription(),SCALE_NORMAL,150,150,150,TRUE,0,2);
$Test->drawGrid(4,TRUE,230,230,230,50);
// Draw the 0 line
$Test->setFontProperties($fontPath . "tahoma.ttf",6);
$Test->drawTreshold(0,143,55,72,TRUE,TRUE);
// Draw the line graph
$Test->drawLineGraph($DataSet->GetData(),$DataSet->GetDataDescription());
$Test->drawPlotGraph($DataSet->GetData(),$DataSet->GetDataDescription(),3,2,255,255,255);
// Set labels
$Test->setFontProperties($fontPath . "tahoma.ttf",8);
$Test->setLabel($DataSet->GetData(),$DataSet->GetDataDescription(),"Serie1","2","Daily incomes",221,230,174);
$Test->setLabel($DataSet->GetData(),$DataSet->GetDataDescription(),"Serie2","6","Production break",239,233,195);
// Finish the graph
$Test->setFontProperties($fontPath . "tahoma.ttf",8);
$Test->drawLegend(600,30,$DataSet->GetDataDescription(),255,255,255);
$Test->setFontProperties($fontPath . "tahoma.ttf",10);
$Test->drawTitle(50,22,$chartTitle,50,50,50,585);
$Test->Render("assets/images/charts/chart.png");
return '<img src="assets/images/charts/chart.png"/>';
?>