Execute paramaters bug?

I am trying to use the parameters feature of the execute for the first
time, and there seems to be a bug.  I all the parameters I set are of
the same type (all numeric, all varchar, etc...), then the call works
fine.  However, if I mix and match, I get some strange errors.  The code
is below.

Also, is there a function, like in Perl::DBI, which will escape a string
so that you can build an SQL string.  It handles strings with quotes,
etc...  I assume if I can get the parameters working, it won't matter.

Thanks,

Chuck

#!/usr/bin/env python -O

if __name__=='__main__':
    import Sybase

    db = Sybase.connect('peach5025d', 'may', 'maymay', 'bsiweb_dev')
    c = db.cursor()

    status_id = 0
    output_text = "OUTPUT"
    error_text = "ABC"
    job_id = 30

    # this works (all numeric fields)
    c.execute('UPDATE jobs SET status_id = @status_id WHERE job_id =
@job_id', \
              { '@job_id' : job_id, '@status_id' : 1 })

    # this doesn't work (one numeric, one varchar), and give the
following error:
    # Traceback (most recent call last):
    #   File "./testd.py", line 19, in ?
    #     { '@error_text' : error_text, '@job_id' : job_id })
    #   File "/opt/net/utils/lib/python2.2/site-packages/Sybase.py",
line 376, in execute
    #     self._start_results()
    #   File "/opt/net/utils/lib/python2.2/site-packages/Sybase.py",
line 548, in _start_results
    #     status, result = self._cmd.ct_results()
    #   File "/opt/net/utils/lib/python2.2/site-packages/Sybase.py",
line 145, in _servermsg_cb
    #     raise DatabaseError(_fmt_server(msg))
    # Sybase.DatabaseError: Msg 1622, Level 18, State 2, Line 1
    # Type 'C' not implemented.
    c.execute("UPDATE jobs SET error_text = @error_text WHERE job_id =
@job_id", \
              { '@error_text' : error_text, '@job_id' : job_id })
    
    # this works (all varchar fields)
    c.execute("UPDATE jobs SET output = @output, error_text =
@error_text WHERE job_id = 30", \
               { '@output' : output_text, '@error_text' : error_text })

    db.commit()