[solved] Graphs are missing in Trees but real Time graphs are OK

[FMJ999]

This is a brand new Cacti install in version 1.2.6 (on Debian 7 with Apache 2).
Everything seem's to work OK : I can login, I can create Devices, I can create Trees, I can create Graphs but Cacti doesn't show correctly those graphs. There's a "missing image symbol" instead of the graphs.
I don't notice any related issue in the logs.
I tried with several browsers : same issue.
But when I clic on rela time graph, the graph is shown correctly in a new window.

An image is better than a speech :

firefox_R6nc0Sb2tp.png (174.68 KiB) Viewed 560 times

[FMJ999]

To illustrate that real time graphs are correctly rendered :

firefox_uYYZi28Qhv.png (340 KiB) Viewed 552 times

[FMJ999]

I'm a bit stupid : this issue is documented in Cacti FAQ. This is a pb with the poller (which is not executed in crontab, I don't know why for the moment but I will figure out).
https://www.cacti.net/downloads/docs/ht ... ml#AEN2469