Twitter Search API is not returning ALL tweets on a given search

My test tweets are not showing up in the twitter search. I have asked several other people to test this as well and only a few show up.

I am trying to track a campaign on the number of people who tweet a certain hashtag. How am I supposed to track it accurately if the search does n开发者_运维问答ot give exact results?

Has anyone else experienced this problem?

I read where the API isn't extremely accurate. It only returns results after a crawl, and may not have crawled the entire database when you're searching. The API also doesn't hold on to tweets longer than a few days old.