The issue could be with the posting account, and not with the hashtag, per se.
If you are only looking for hashtags programatically, consider using the track parameter on the Streaming API. You will see single character hashtags there, along with a lot of spurious matches like #I'malittleteapot. -John Kalucki http://twitter.com/jkalucki Services, Twitter Inc. On Sep 18, 11:36 am, Nobu Funaki <nob.fun...@gmail.com> wrote: > Hi, > > I'm talking about hashtag. > > I tried to use #A, #B or #C whatever one letter hashtag, sometimes > couldn't find them in search result. But sometimes I could. > > Could you tell me if there is any certain rules? Perhaps it is > involved this rule. > > - Misuse of hashtags (words followed by the '#' > sign)http://help.twitter.com/forums/10713/entries/42646 > > I'm not sure, but two letters works well. The document just says that > hashtag should be up to 16 > characters.http://apiwiki.twitter.com/Twitter-Search-API-Method%3A-search > > Thank you, > > Nobu