I'm using the api in my own application, which is in php5 and uses an __autoload() function to include classes.
The ResultConverter calls class_exists($strClass) to know if XML.php or HTML.php are present. The bug is that class_exists() will use my __autoload() by default, which in my case is not designed to understand the api class structure. So to be able to use php build-in methods, class_exists should be called like this: class_exists($strClass, FALSE)
With the "FALSE" parameter, my __autoload() function isn't called and that what we should want.
Bug on line 86 in api/sparql/SparqlEngine/ResultConverter.php