[SR-Users] Nathelper ping from dedicated kamailio instance

Hi! I am new to kamailio so please forgive me if I write some errors. I am configuring some kamailio instances in different environments to handle big traffic and I have a problem with usrloc + db + nathelper. What have I done: 1. Configured a kamailio instance to handle sip registers with usrloc to database with database mode 2 (memory + db), disabled nathelper pings. This is ok and performs well; 2. Configured a kamailio instance to handle nathelper ping. Same usrloc + db + nathelper config from 1 except that I use db mode 3 (only db) and that I enabled natping_interval . My problem is that it seems that the second kamailio instance does not send pings. The second one connects correctly to db (if I lookup from kamcmd a user registered from the first kamailio I can find it) but it seems that does not read all locations. Can you help me? Many many thanks Angelo