Data lines and data hits but no sessions

[GVLabs]

Hello, I've just set up Urchin v6 at a portal in a development
environment, not visible from the internet but visible to our urchin
server.

The architecture is as follows:
- 2x Apache as frontal server (users connect to the apache server)
- 1x Tomcat as app server
- Database server

The log format has been configured in the frontal servers and the
result is the following:
172.17.6.152 previlr.gva.es - [23/Jan/2012:08:28:49 +0100] "GET /
resources/v2/img/boton-twitter_32.jpg HTTP/1.1" 200 1120 "http://
previlr.gva.es/web/portal/inicio/presentacion" "Mozilla/5.0 (Windows
NT 5.1; rv:9.0.1) Gecko/20100101 Firefox/9.0.1"
"GUEST_LANGUAGE_ID=ca_ES;
__utma=128657357.878271155.1326975036.1326979605.1327048059.4;
__utmz=128657357.1326975036.1.1.utmccn=(direct)|utmcsr=(direct)|
utmcmd=(none); COOKIE_SUPPORT=true;
JSESSIONID=GpS5PdMDJLpL2nzxKwLlJtfCwBJCPM6RckbTnYPDKGW208ffd8Z6!-245101894"

Both __utm.gif and urchin.js can bee seen at the log, however after
processing the log from urchin the result is as follows:
[08:45:52] Logfile: /usr/local/urchin/var/urchin-10-0.log
[08:45:52] Logfile: /usr/local/urchin/var/urchin-11-1.log
data lines: 200 (100%)
data hits: 200
data proc: 122.32 KB in 00:00:01 (0.119 MB/sec)
data range: 2012-01-23 08:20 (0100) - 2012-01-23 08:30 (0100)

[08:45:52] Post processing data for 201201
sessions: 0 (100%)

Any help would be appreciated.

Victor.