rss to twitter cache

Seems there is a problem with the cache.... sometimes it saves to feed.log.txt sometimes not... as a result, sometimes the entire feed gets reposted, and also, sometimes the last 1 or 2 articles do not get posted.  Any help or suggestions?

Maybe a permissions problem? You are running the script with the same rights each time?

I'm actually working on having the feed be indexed in a DB before posting... that way I can be sure
of no duplicates.  One problem with this version is that if I post to twitter myself (ie on twitter.com) the entire feed gets re-posted because the URL makes the message appear to twitter different than the previously posted comments that are exactly the same (this is due to using the URL shortenener).  As for the feedlog problem, the pattern seems to be if I post twice without a change to the RSS feed.