fixed an issue when a serie name was not set, thus generating a warning

libraries/chart/pma_pchart_chart.php

@@ -296,7 +296,7 @@ abstract class PMA_pChart_chart extends PMA_chart
         $this->prepareChart();
 
         //$this->chart->debugImageMap();
-        $this->chart->printErrors('GD');
+        //$this->chart->printErrors('GD');
 
         // check if a user wanted a chart in one part
         if ($this->isContinuous()) {

libraries/chart/pma_pchart_single.php

@@ -49,6 +49,7 @@ abstract class PMA_pChart_single extends PMA_pChart_chart
 
         $this->dataSet->SetXAxisName($this->getXLabel());
         $this->dataSet->SetYAxisName($this->getYLabel());
+        $this->dataSet->SetSerieName($this->getYLabel(), "Values");
     }
 }
 

libraries/chart/pma_pchart_single_bar.php

@@ -26,6 +26,7 @@ class PMA_pChart_single_bar extends PMA_pChart_single
     protected function drawChart()
     {
         // Draw the bar chart
+        // use stacked bar graph function, because it gives bars with alpha
         $this->chart->drawStackedBarGraph($this->dataSet->GetData(),$this->dataSet->GetDataDescription(),70);
     }
 }