The search functions don't work

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.