12.04 - Hardware Enablement Stack (HWE) out of support

From yesterday my update manager gives me this message:

Your current Hardware Enablement Stack (HWE) is going out of support
on 07/08/2014. After this date security updates for critical parts (kernel
and graphics stack) of your system will no longer be available.

For more information, please see: http://wiki.ubuntu.com/1204_HWE_EOL

But when I try to upgrade the HWE with the command suggested by hwe-support-status --verbose that is

sudo apt-get install linux-generic-lts-trusty libgl1-mesa-glx-lts-trusty xserver-xorg-lts-trusty linux-image-generic-lts-trusty

I get dependency errors:

Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libgl1-mesa-glx-lts-trusty : Depends: libglapi-mesa-lts-trusty (= 10.1.3-0ubuntu0.1~precise1) but it is not going to be installed
 xserver-xorg-lts-trusty : Recommends: xserver-xorg-input-all-lts-trusty but it is not going to be installed
                           Recommends: xserver-xorg-video-all-lts-trusty but it is not going to be installed
                           Recommends: x11-xserver-utils-lts-trusty but it is not going to be installed
                           Conflicts: libglapi-mesa:i386 (>= 0~)
E: Unable to correct problems, you have held broken packages.

How can I solve this?

I'm running Ubuntu 12.04.4 LTS 64 bit with kernel 3.5.0-53-generic.