gksu - nuew administrator needs password of previous administrator

[BlauesEi]

I created a new user (2nd-user) that will work as administrator.

He belongs to the group admin and sudo

2nd user kann work with the sudo command without any problems.
+++++++++++++++++++++++++++++++++++++
That happens:

but when 2nd-user wants to use the command:
gksu
his password will not be accepted. Only the password of the 1st-user - who has still admin-rights - will be accepted.

2nd-user can not use gksudo.

gksu and gksudo works differently.
When I use gksu at 2nd-user I need password of 1st-user.
Gksu works at 2nd-user neither nor
Here will I report what I have done:

When I am logged in as 1st-user:
Keabordshortcut Control+Shift+r launch nautilus as root
with password of 1st user it will open.

I open terminal
Gksu gedit
is OK
gksudo gedit
Can not open display

DISPLAY=:0 gksudo gedit
Can not open display

I log in as 2nd user

the command sudo works so far for this user.
I can install and remove packages, I can change user with sudo su etc.
Here will be the password for 2nd-user requiered and it works fine.

With keyboardshortcut Control+shift+r I launch nautilus as root
Only with pasword for 1st-user I can open it.

I open the terminal:
gksu gedit
only with password of 1st-user I can open it.

gksu gedit
with password of 2nd-user
Will be ignored without comment, system returns to to terminal

gksudo gedit
I type in password of 2nd-user

Display can not be opend

gksudo gedit
with password of 1st-user
will not accepted

DISPLAY=:0 gksudo gedit
only password of 2nd-user will be accepted but it will not open

Can not open display

 ++++++++++++++++++++++++++++++
What should happen?

the new administrator (2nd-user) should use his password for sudo and for gksu.
Also I should use the gksudo command

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gksu 2.0.2-6ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic i686
ApportVersion: 2.0.1-0ubuntu5
Architecture: i386
Date: Wed Sep 12 16:20:32 2012
InstallationMedia: Vinux 3.0 - Release i386
ProcEnviron:
 LANGUAGE=de_DE:de:en_GB:en
 PATH=(custom, no user)
 LANG=de_DE.utf8
 SHELL=/bin/bash
SourcePackage: gksu
UpgradeStatus: No upgrade log present (probably fresh install)