JPgraph มัน แจ้งว่า JpGraph Error: 25070 Either X or Y data arrays contains non-numeric values.

<?php 
include_once '../jpgraph-3.5.0b1/src/jpgraph.php';
include_once '../jpgraph-3.5.0b1/src/jpgraph_bar.php';
include_once '../jpgraph-3.5.0b1/src/jpgraph_line.php';

$objConnect = mysql_connect("localhost","root","1234") or die ("Error connect to Database");
$objDB = mysql_select_db("db_iservice");
mysql_query("SET NAMES UTF-8");
$strSQL = "SELECT * FROM requests WHERE id ='282'";
$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");

$datay =array();
$d = array();
while($objResult = mysql_fetch_array($objQuery)){
$datay[] =
$objResult["service_code"];
$d[] = $objResult["device_name"];
}
$graph = new Graph(940.400);
$graph->SetScale("textlin");
$graph->xaxis->SetTickLabels($id);
$graph->xaxis->SetLabelAngle(90);

$graph->img->SetAngle(0);
$bplot = new BarPlot($datay);
$bplot->SetFillColor('#EDF5FF');
$bplot->SetWidth(0.6);
$bplot->SetPattern(PATTERN_CROSS1,'navy');
$graph->SetMarginColor('#EDF5FF');
$graph->SetFrame(true,'#EDF5FF',2);
$graph->SetColor('#EDF5FF');
$graph->Add($bplot);
$graph->Stroke();

?>