It told me at the end of the installation progress triggered from additional drivers.

Sorry, installation of this driver failed.

Please have a look at the log file for details: /var/log/jockey.log

And this is the end of the jockey log file:

Setting up fglrx (2:8.840-0ubuntu4) ...
Loading new fglrx-8.840 DKMS files...
Building for 2.6.35-28-generic and 2.6.38-8-generic
Building for architecture x86_64
Module build for the currently running kernel was skipped since the
kernel source for this kernel does not seem to be installed.
Building initial module for 2.6.38-8-generic
Done.

fglrx.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/2.6.38-8-generic/updates/dkms/

depmod.....

DKMS: install Completed.
update-initramfs: deferring update (trigger activated)
Processing triggers for python-gmenu ...
Rebuilding /usr/share/applications/desktop.POSIX.cache...
Processing triggers for bamfdaemon ...
Rebuilding /usr/share/applications/bamf.index...
Setting up fglrx-amdcccle (2:8.840-0ubuntu4) ...
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-2.6.38-8-generic
Processing triggers for python-support ...

2011-04-29 22:52:08,066 WARNING: modinfo for module fglrx failed: ERROR: modinfo: could not find module fglrx

2011-04-29 22:52:08,066 WARNING: /sys/module/fglrx/drivers does not exist, cannot rebind fglrx driver
2011-04-29 22:52:08,066 ERROR: XorgDriverHandler.enable(): package or module not installed, aborting
2011-04-29 22:52:20,284 DEBUG: XorgDriverHandler(%s, %s).enabled(): No X.org driver set, not checking
2011-04-29 22:52:20,291 DEBUG: XorgDriverHandler(%s, %s).enabled(): No X.org driver set, not checking