Cacti on Debian Sarge - Driving me crazy

[mcabrerizo]

Hi,
I have recently installed cacti version 0.8.6c which comes with the stable Debian version (.deb packages)

Well, I have access though the web gui and I have my cactid poller working.

I am trying desperately to get some interfaces statistics of my routers, and I follow this steps:
1) Create a Router template so I can get interfaces traffic info
2) Create a new device
3) Once I check Cacti tells me this device is up I create a new graphic from the devices page (the url above tells me I can do this)
4) I select the interface I want to check from the ones listed through SNMP
5) But when I try to view my graphs RRDTool is saying that the rrd file... not such file or directory, the files are not being created in /var/lib/cacti/rra

I have tried to check permissions but something weird is happening am I missing something

Thx for your help