need help on gchart

[eluser]Nano HE[/eluser]
Hi,

I followed the wiki artichle (http://codeigniter.com/wiki/gchart/revision/5312/) to practice google chart in my CI 2.0.
But it doesn't work.

controller file: ci\application\helpers\mytest.php

Code:

$this->load->helper( 'gchart' );
$this->load->view('my_test');

view file: ci\application\helpers\my_test.php

Code:

<?php
$encoded_data = extendedencode(array(0, 1, 2, 3, 4, 5, 6) &maxvalue;);
echo <<< EOS
     <img src="
        http://chart.apis.google.com/chart?
            cht=lc
            &chs=250x250
            &chd;:e{$encoded}
        "
        alt="line graph of some example data" />
EOS;
?&gt;

help file: ci\application\helpers\gchart_helper.php

Code:

// I do copied all the source code from the wiki url link above.

When I try to charted by CI.
It showed error as this,
Parse error: syntax error, unexpected ';' in C:\xampp\htdocs\demo\ci\application\views\my_test.php on line 54

Any thing wrong on my operation?
I compared the extendedencode() from gchart_helper.php

Code:

function extendedencode($data, &$maxvalue='notspecified')

and extendedencode() from my_test.php

Code:

$encoded_data = extendedencode(array(0, 1, 2, 3, 4, 5, 6) &maxvalue;);

Then I updated the extendedencode() line to this in my_test.php view file,

Code:

$encoded_data = extendedencode(array(0, 1, 2, 3, 4, 5, 6), &maxvalue;);

And try again, but still get this error below.
Parse error: syntax error, unexpected ')', expecting T_PAAMAYIM_NEKUDOTAYIM in C:\xampp\htdocs\demo\ci\application\views\my_test.php on line 54

Any help and comments are great appreciated.