[Serusers] fr_inv_timer + avp not working under high load

Hi list, I am trying to realise dynamic invite-timeout-timers loading timer-settings per call from my database using avp. It seems to work perfectly on my development-system but fails nearly completly in my high loaded life-environment. According to my logs, timer values are set correctly (eg.: reply_received: FR_INV_TIMER = 15, see modules/tm/t_reply.c:1371), but most of the times the timers have no effect. My setup is similar to http://siprouter.onsip.org/doc/gettingstarted/ch09.html, but avps are not written by hand, but acquired with: modparam("tm", "fr_inv_timer_avp", "mytimer"); avp_db_load("$ruri/username","s:mytimer"); 'mytimer' is an attribute in an usr_preferences-table. Ser's version is 0.9.6. I already searched the list-archives without finding anything regarding this issue. I Also failed accessing the bug-tracker (http://bugs.sip-router.org/), it gave me an internal server error. Has anybody experienced this effect? Is this a bug? Is there a workaround? Best regards, Marcus Hunger