The search functions don't work

[dubis]

Hi,

The search functions don't work in Kmail. I've got respond from the search widows and the last search directory is blanck.

More system information

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.2 LTS"

:~$ sudo apt policy baloo
baloo:
  Installé : 4:5.36.0-0ubuntu1~ubuntu16.04~ppa1
  Candidat : 4:5.36.0-0ubuntu1~ubuntu16.04~ppa1
 Table de version :
 *** 4:5.36.0-0ubuntu1~ubuntu16.04~ppa1 500
        500 http://ppa.launchpad.net/kubuntu-ppa/backports/ubuntu xenial/main amd64 Packages
        500 http://ppa.launchpad.net/kubuntu-ppa/backports/ubuntu xenial/main i386 Packages
        100 /var/lib/dpkg/status
     4:5.18.0-0ubuntu1.1 500
        500 http://fr.archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
        500 http://fr.archive.ubuntu.com/ubuntu xenial-updates/universe i386 Packages
     4:5.18.0-0ubuntu1 500
        500 http://fr.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        500 http://fr.archive.ubuntu.com/ubuntu xenial/universe i386 Packages

:~$ sudo apt policy kmail
kmail:
  Installé : 4:16.04.3-0ubuntu2~ubuntu16.04~ppa63
  Candidat : 4:16.04.3-0ubuntu2~ubuntu16.04~ppa63
 Table de version :
 *** 4:16.04.3-0ubuntu2~ubuntu16.04~ppa63 500
        500 http://ppa.launchpad.net/kubuntu-ppa/backports/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status
     4:15.12.3-0ubuntu1 500
        500 http://fr.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages

KDE bug tracking team told me to use the last version (5.5.x) or 5.6.x

Thank for your support.