JpGraph error on the poll results page

On the polls results page you can see the error:

JpGraph PHP error : Non-static method system ::getpage() should not be called statically

You need to do the following:

open the file /system/ext/jpgraph/jpg-config.inc,

change the line:

DEFINE("CATCH_PHPERRMSG",true);

to:

DEFINE("CATCH_PHPERRMSG",false);