[phpOpenTracker-general] phpOpenTracker does not create graphs

Hi.

Sorry for bothering you again, but I can't get phpopentracker working
with graphs. I did everything as described on the website and it
collects all the user data and the example "simple_report" works fine
instead of the graphs. The graph in this example is not shown and their
is no file in any /tmp direction. When I tried one of the examples of
jpgraph, everything works fine and the png-file is in the specified
directory.

I'm using phpOpenTracker 1.5.2. Is this the right version or should I
have another one. I'm really not lazy and I would be very thanksful if
anyone could explain me a way how to debug this.

Please help me, because the graphs are the reason, why I chose
phpOpenTracker.

Thank you very much in advance.

Best regards.

Roman