DbfilenameShelf instance has no attribute 'writeback'

[warren ali]

Anyone have any idea why this is failing with the following error

class _IndexFile:
"""An _IndexFile is an implementation class that presents a
Sequence and Dictionary interface to a sorted index file."""

def __init__(self, pos, filenameroot):
self.pos = pos
self.file = open(_indexFile Pathname(filena meroot), _FILE_OPEN_MODE )
self.offsetLine Cache = {} # Table of (pathname, offset) -> (line,
nextOffset)
self.rewind()
self.shelfname = os.path.join(WN SEARCHDIR, pos + ".pyidx")
try:
import shelve
self.indexCache = shelve.open(sel f.shelfname, 'r')
except:
pass

Exception exceptions.Attr ibuteError: "DbfilenameShel f instance has no
attribute 'writeback'" in Exception exceptions.Attr ibuteError:
"DbfilenameShel f instance has no attribute 'writeback'" in Exception
exceptions.Attr ibuteError: "DbfilenameShel f instance has no attribute
'writeback'" in Exception exceptions.Attr ibuteError: "DbfilenameShel f
instance has no attribute 'writeback'" in

The code still returns the correct restults but each result come back
with this exception.