gdm can't start LXDE through standard script startlubuntu

[mikhail-777]

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
$ lsb_release -rd
Description: Ubuntu 12.04.1 LTS
Release: 12.04

2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
$ apt-cache policy gdm
gdm:
  Installed: 3.0.4-0ubuntu15.3
  Candidate: 3.0.4-0ubuntu15.3
  Version table:
 *** 3.0.4-0ubuntu15.3 0
        500 http://mirror.yandex.ru/ubuntu/ precise-updates/universe i386 Packages
        100 /var/lib/dpkg/status
     3.0.4-0ubuntu15 0
        500 http://mirror.yandex.ru/ubuntu/ precise/universe i386 Packages
     2.30.2.is.2.30.0-0ubuntu5.2 0
        500 http://ubuntu.mirror.cambrium.nl/ubuntu/ lucid-updates/main i386 Packages

3) What you expected to happen?
I tried to login through gdm to LXDE.
I entered username, password, session type and pressed login button.
I expected LXDE session start.

4) What happened instead?
I tried to login through gdm to LXDE.
I entered username, password, session type and pressed login button.
gdm dissapeared, then gdm restarted.
No LXDE session started.

5) Then I created /usr/share/xsessions/MyLubuntu.desktop with content:
[Desktop Entry]
# The names/descriptions should really be better
Name=MyLubuntu
Comment=Lubuntu - Lightweight X11 desktop environment based on LXDE
Comment[zh_TW]=Lubuntu - 輕量級的 X11 桌面環境
Comment[fi]=Lubuntu - kevyt X11-työpöytäympäristö
Comment[ja]=Lubuntu - 軽量な X11 デスクトップ環境
Exec=/usr/bin/lxsession -s Lubuntu -e LXDE
# Icon=
Type=Application

6) Then I can login through gdm to MyLubuntu, which start binary /usr/bin/lxsession directly.

7) But I can't login when gdm try to start script /usr/bin/startlubuntu

8) Also I tried to comment in /usr/bin/startlubuntu everything exept
exec /usr/bin/lxsession -s Lubuntu -e LXDE

9) But it does not not help.

10) $ apt-cache policy lxsession
lxsession:
  Installed: 0.4.6.1+git20120214-0ubuntu1
  Candidate: 0.4.6.1+git20120214-0ubuntu1
  Version table:
 *** 0.4.6.1+git20120214-0ubuntu1 0
        500 http://mirror.yandex.ru/ubuntu/ precise/universe i386 Packages
        100 /var/lib/dpkg/status

11) Package for /usr/bin/startlubuntu and /usr/share/xsessions/Lubuntu.desktop :
$ apt-cache policy lubuntu-default-settings
lubuntu-default-settings:
  Installed: 0.27
  Candidate: 0.27
  Version table:
 *** 0.27 0
        500 http://mirror.yandex.ru/ubuntu/ precise/universe i386 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gdm 3.0.4-0ubuntu15.3
ProcVersionSignature: Ubuntu 3.2.0-67.101-generic-pae 3.2.60
Uname: Linux 3.2.0-67-generic-pae i686
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: i386
Date: Sat Aug 2 19:44:57 2014
InstallationMedia: Ubuntu-Studio 10.10 "Maverick Meerkat" - Release i386 (20101008)
MarkForUpload: True
SourcePackage: gdm
UpgradeStatus: Upgraded to precise on 2012-10-23 (648 days ago)