Exception raised by tbwiki software

Traceback (most recent call last):
  File "tbwiki.cgi", line 54, in 
    main(req)
  File "/home2/birdorg/work/tbwiki/cgi-bin/tbwiki_engine.py", line 3257, in main
    data = call_processor(action_processor, action_function, req, content)
  File "/home2/birdorg/work/tbwiki/cgi-bin/tbwiki_engine.py", line 1939, in call_processor
    return processor_func(req)
  File "/home2/birdorg/work/tbwiki-data/tbwiki/plugins/ProcessorUserChoice.py", line 50, in choice1
    block_name = req.form["block_name"].value
  File "/usr/lib64/python2.7/cgi.py", line 540, in __getitem__
    raise KeyError, key
KeyError: 'block_name'