icingaweb2 version ... undefined

in the intercace 'system / about' i have :
Can't determine Icinga Web 2's version


my question is :
is it normal?

os : debian 8.1 with icinga repository
icinga version : r2.3.8-1
db : postgresql 9.4
icinga :
icinga2=# select * from icinga_dbversion;
dbversion_id | name | version | create_time | modify_time
--------------+----------+---------+-------------------------------+-------------------------------
1 | idoutils | 1.13.0 | 2015-07-20 15:09:23.277165+02 | 2015-07-20 15:09:23.277165+02
icingaweb2 : undefined, find below the list of tables :
icingaweb=# \dt
Liste des relations
Schéma | Nom | Type | Propriétaire
--------+----------------------------+-------+----------------
public | icingaweb_group | table | icingaidoutils
public | icingaweb_group_membership | table | icingaidoutils
public | icingaweb_user | table | icingaidoutils
public | icingaweb_user_preference | table | icingaidoutils

thank you for your help