bulk accept submission crashes

ValueError at /conferences/myadmin/bulk_accept_submissions/
invalid literal for int() with base 10: ''
Request Method: GET
Request URL: http://konferencia.mktudegy.hu/conferences/myadmin/bulk_accept_submissions/
Exception Type: ValueError
Exception Value:
invalid literal for int() with base 10: ''
Exception Location: /home/coauthors/webapps/konferencia/webapp/conference/views.py in bulk_accept_submissions, line 145
Python Executable: /usr/local/bin/python
Python Version: 2.5.2
Python Path: ['/home/coauthors/webapps/konferencia', '/home/coauthors/webapps/konferencia/lib/python2.5', '/home/coauthors/webapps/konferencia/webapp', '/home/coauthors/lib/python2.5', '/usr/local/lib/python2.5/site-packages/MySQL_python-1.2.2-py2.5-linux-i686.egg', '/usr/local/lib/python2.5/site-packages/setuptools-0.6c8-py2.5.egg', '/usr/local/lib/python2.5/site-packages/python_memcached-1.41-py2.5.egg', '/home/coauthors/webapps/konferencia/lib/python2.5', '/usr/local/lib/python25.zip', '/usr/local/lib/python2.5', '/usr/local/lib/python2.5/plat-linux2', '/usr/local/lib/python2.5/lib-tk', '/usr/local/lib/python2.5/lib-dynload', '/usr/local/lib/python2.5/site-packages', '/usr/local/lib/python2.5/site-packages/PIL']
Server time: Tue, 7 Jul 2009 13:41:27 -0500