Brocken Image Link Accurate Billing

Hello,
in Version 0.14.8.5742 I cant see it the Biling the accurate Graph. I get an error: JpGraph Error: 25008. The link hat will build is like: billing-graph.php?bill_id=3&bill_code=&from=1408010243&to=1408096643&x=1230&y=300$imgtype
In accurate.inc.php I fixed it in line 24,32 and 40 with
$graph .= '$imgtype" alt="">'; to $graph .= '&imgtype" alt="">';