I've a custom port that is working fine with me, thats the only special thing in my native installation that comes to mind, but when try to perform an upgrade this is the error that I'm having:

me@stream:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
airtime linux-generic linux-headers-generic linux-image-generic liquidsoap
0 upgraded, 0 newly installed, 0 to remove and 5 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue [Y/n]? y
Setting up airtime (2.1.3-1) ...
Site airtime-vhost disabled.
Run '/etc/init.d/apache2 reload' to activate new configuration!
Setting up apache2...
Module rewrite already enabled
Configuring php5...
Setting up monit configuration...
Stopping daemon monitor: monit.
Starting daemon monitor: monit.
www-data www-data 750 /srv/airtime
dpkg-statoverride: warning: An override for '/srv/airtime' already exists, but - so will be ignored.
* Restarting web server apache2 ... waiting
Liquidsoap symlink points to the right place!
Reinstallation detected...

Debian package of Airtime detected...

* Making sure /etc/default/locale is set properly
LANG="en_US.UTF-8"
* Checking for existing Airtime installation...
* Temporarily stopping any previous running services

******************************** Install Begin *********************************
Ensuring python-virtualenv version > 1.4.8...Success!

*** Creating Virtualenv for Airtime ***
Already using interpreter /usr/bin/python
New python executable in /usr/lib/airtime/airtime_virtualenv/bin/python
Installing distribute.................................................................................................................................................done.

*** Installing Python Libraries ***
Unpacking /var/lib/airtime/tmp/python_apps/python-virtualenv/airtime_virtual_env
Downloading/unpacking mutagen
Running setup.py egg_info for package mutagen

Downloading/unpacking kombu
Running setup.py egg_info for package kombu

Downloading/unpacking pytz
Running setup.py egg_info for package pytz

warning: no files found matching '*.pot' under directory 'pytz'
warning: no previously-included files found matching 'test_zdump.py'
Downloading/unpacking configobj
Running setup.py egg_info for package configobj

Downloading/unpacking poster
Running setup.py egg_info for package poster

Downloading/unpacking pyinotify
Running setup.py egg_info for package pyinotify

Downloading/unpacking amqplib
Running setup.py egg_info for package amqplib

Downloading/unpacking anyjson
Running setup.py egg_info for package anyjson

Installing collected packages: amqplib, anyjson, configobj, kombu, mutagen, postytz
Running setup.py install for amqplib

Running setup.py install for anyjson

Running setup.py install for configobj

Running setup.py install for kombu

Running setup.py install for mutagen
changing mode of build/scripts-2.7/mid3iconv from 644 to 755
changing mode of build/scripts-2.7/mutagen-inspect from 644 to 755
changing mode of build/scripts-2.7/mid3v2 from 644 to 755
changing mode of build/scripts-2.7/moggsplit from 644 to 755
changing mode of build/scripts-2.7/mutagen-pony from 644 to 755

changing mode of /usr/lib/airtime/airtime_virtualenv/bin/mid3iconv to 755
changing mode of /usr/lib/airtime/airtime_virtualenv/bin/mutagen-inspect to
changing mode of /usr/lib/airtime/airtime_virtualenv/bin/mid3v2 to 755
changing mode of /usr/lib/airtime/airtime_virtualenv/bin/moggsplit to 755
changing mode of /usr/lib/airtime/airtime_virtualenv/bin/mutagen-pony to 755
Running setup.py install for poster

Running setup.py install for pyinotify

Running setup.py install for pytz

warning: no files found matching '*.pot' under directory 'pytz'
warning: no previously-included files found matching 'test_zdump.py'
Successfully installed amqplib anyjson configobj kombu mutagen poster pyinotify
Cleaning up...

*** Patching Python Libraries ***
* Patching virtualenv libraries in /usr/lib/airtime/airtime_virtualenv/lib/pyth

---Applying Patches for mutagen---
patching file site-packages/mutagen/mp3.py
Hunk #2 succeeded at 169 (offset -4 lines).
patching file site-packages/mutagen/mp3.py
Hunk #1 succeeded at 204 (offset -5 lines).
* Checking for user pypo
User already exists.
* Airtime Version: 2.1.3
* Storage directory setup
* Skipping directory already exists: /srv/airtime/stor
* Giving Apache permission to access /srv/airtime/stor
* Skipping directory already exists: /srv/airtime/stor/organize
* Giving Apache permission to access /srv/airtime/stor/organize
* Checking database for correct encoding

* Database Installation
* Creating Airtime database user
* Database user 'airtime' created.
* Creating Airtime database
* Database 'airtime' already exists.
* Postgres scripting language already installed

Database already exists. Do you want to delete all tables and recreate? (y/N) * version
* Creating /etc/airtime
* Creating /etc/monit/conf.d/monit-airtime-generic.cfg
* Creating /etc/cron.d/airtime-crons
* Creating /usr/lib/airtime
* Creating symbolic links in /usr/bin
* Creating /var/log/airtime
* Creating /usr/share/airtime
* Creating /var/log/airtime
* Creating /var/tmp/airtime
* Waiting for media-monitor processes to start...
Starting Airtime Media Monitor: Done.
* Detecting OS: ... Found Ubuntu 11.04 (natty) on amd64 architecture
* Clearing previous pypo cache
* Waiting for pypo processes to start...
Stopping daemon monitor: monit.
Starting daemon monitor: monit.

*** Verifying your system environment, running airtime-check-system ***
AIRTIME_STATUS_URL = http://localhost:8443/api/status/format/json/ap%
AIRTIME_SERVER_RESPONDING = OK
KERNEL_VERSION = UNKNOWN
MACHINE_ARCHITECTURE = UNKNOWN
TOTAL_MEMORY_MBYTES = UNKNOWN
TOTAL_SWAP_MBYTES = UNKNOWN
AIRTIME_VERSION = UNKNOWN
OS = Ubuntu 11.04 x86_64
CPU = Intel(R) Xeon(R) CPU E5606 @ 2.13GHz
WEB_SERVER = A
PLAYOUT_ENGINE_PROCESS_ID = FAILED
PLAYOUT_ENGINE_RUNNING_SECONDS = 0
PLAYOUT_ENGINE_MEM_PERC = 0%
PLAYOUT_ENGINE_CPU_PERC = 0%
LIQUIDSOAP_PROCESS_ID = FAILED
LIQUIDSOAP_RUNNING_SECONDS = 0
LIQUIDSOAP_MEM_PERC = 0%
LIQUIDSOAP_CPU_PERC = 0%
MEDIA_MONITOR_PROCESS_ID = FAILED
MEDIA_MONITOR_RUNNING_SECONDS = 0
MEDIA_MONITOR_MEM_PERC = 0%
MEDIA_MONITOR_CPU_PERC = 0%
RABBITMQ_PROCESS_ID = FAILED
RABBITMQ_RUNNING_SECONDS = 0
RABBITMQ_MEM_PERC = 0%
RABBITMQ_CPU_PERC = 0%

-- There appears to be a problem with your Airtime installation.

-- Please visit http://wiki.sourcefabric.org/x/HABQ
dpkg: error processing airtime (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
airtime
E: Sub-process /usr/bin/dpkg returned an error code (1)

after this error I have to re enable apache site for airtime to have my old installation working again, could anyone help  me with this?

thank you