Cacti

When I executed graph.ph manually some errors come into view. /usr/share/cacti/site/rra# su - cacti $ php /usr/share/cacti/site/graph.php Warning: main(./include/auth.php): failed to open stream: No such file or directory in /usr/share/cacti/site/graph.php on line 32 Warning: main(): Failed opening ...

When I try to see the graph appears the message

"rrdtool says: graph access denied"

and I cannot see any graph

I have a debian 3.1,
mysql-server-5.0 (version 5.0.18-3.dotdeb.1 )
cacti 0.8.6c-7sarge2