Error on build

I obtain this error of missing file when execute falcon-build-queue, but the package is installed correctly in the repository

angel@marvin:~/.falcon/rootdir/.falcon$ falcon-build-queue -i -v
Falcon repository manager 2.0.3 (C)2005-2008 Dennis Kaarsemaker <email address hidden>
D: Reading file /var/www/falcon/.falcon/incoming/hello-debhelper_2.1.1-5_source.changes
D: Parsing /var/www/falcon/.falcon/incoming/hello-debhelper_2.1.1-5.dsc
D: Reading file /var/www/falcon/.falcon/incoming/hello-debhelper_2.1.1-5.dsc
* Building hello-debhelper_2.1.1-5.dsc on Angel
* Uploading hello-debhelper 2.1.1-5 for building on amd64 buildd Angel
D: Executing: ['rsync', '.falcon/build/building/hello-debhelper_2.1.1-5.dsc', '127.0.0.1:/home/angel/builder/incoming']
D: Executing: ['rsync', '.falcon/build/building/hello-debhelper_2.1.1.orig.tar.gz', '127.0.0.1:/home/angel/builder/incoming']
D: Executing: ['rsync', '.falcon/build/building/hello-debhelper_2.1.1-5.diff.gz', '127.0.0.1:/home/angel/builder/incoming']
* Trying to build on Angel
* Executing the build command, logging to buildlog_pastelero-unstable-amd64.hello-debhelper_2.1.1-5_BUILDING.txt
D: Executing: ['ssh', '127.0.0.1', '/home/angel/builder/unstable-build.sh', 'build', '/home/angel/builder/incoming/hello-debhelper_2.1.1-5.dsc']
D: Executing: ['gzip', '-f', '/var/www/falcon/.falcon/build/logs/buildlog_pastelero-unstable-amd64.hello-debhelper_2.1.1-5_FULLYBUILT.txt']
* Checking build status of hello-debhelper 2.1.1-5 on amd64 buildd Angel
D: Executing: ['rsync', '127.0.0.1:/home/angel/builder/result/hello-debhelper_2.1.1-5_amd64.changes', '.falcon/build/building']
* Downloading hello-debhelper_2.1.1-5.dsc
D: Executing: ['rsync', '127.0.0.1:/home/angel/builder/result/hello-debhelper_2.1.1-5.dsc', '.falcon/build/building']
* Downloading hello-debhelper_2.1.1-5.diff.gz
D: Executing: ['rsync', '127.0.0.1:/home/angel/builder/result/hello-debhelper_2.1.1-5.diff.gz', '.falcon/build/building']
* Downloading hello-debhelper_2.1.1-5_amd64.deb
D: Executing: ['rsync', '127.0.0.1:/home/angel/builder/result/hello-debhelper_2.1.1-5_amd64.deb', '.falcon/build/building']
* Checking for debug symbol package hello-debhelper-dbgsym_2.1.1-5_amd64.ddeb
D: Executing: ['rsync', '127.0.0.1:/home/angel/builder/result/hello-debhelper-dbgsym_2.1.1-5_amd64.ddeb', '.falcon/build/building']
* Succeeded building hello-debhelper 2.1.1-5 on amd64 buildd Angel
* Build result for hello-debhelper 2.1.1-5
* ========================================
* amd64 Angel OK
* Completely built hello-debhelper 2.1.1-5
D: Reading file /var/www/falcon/.falcon/build/building/hello-debhelper_2.1.1-5.dsc
D: Reading file pool/unstable/main/hello-debhelper_2.1.1-5.dsc
D: Reading file /var/www/falcon/.falcon/incoming/hello-debhelper_2.1.1-5.dsc
D: File /var/www/falcon/.falcon/incoming/hello-debhelper_2.1.1-5.dsc can't be read

 === ERROR! ===

An error occured in falcon-build-queue. This is probably a bug in the software.
Please file a bug at https://launchpad.net/falcon/+filebug and
include the following backtrace:

Traceback (most recent call last):
  File "/usr/bin/falcon-build-queue", line 94, in ?
    control, controlfields, files = falcon.package.parse_dsc(os.path.join(incoming, dsc))
  File "/usr/lib/python2.4/site-packages/falcon/package.py", line 302, in parse_dsc
    dsc = unicode(dsc.strip(), chardet.detect(dsc.strip())['encoding']).encode('utf-8')
TypeError: unicode() argument 2 must be string, not None