Deleting Your Tweets - it will detete tweets, but still only limited

before i start, i would like to say, i have tried to remove all tweets at any one time, it does work, but its only limited, most will delete 200 at any one go, after you used the site or sites, then you can't remove nomore, i don't know why this happens, its like the site or sites gives up on you after a while or the sites cannot find any of your tweets.
 
http://www.deleteallmytweets.com/ 

Delete All My Tweets is an app which does what it says on the tin.

If you want to delete all tweets from your Twitter account simply sign in with Twitter, autorise the app, click to confirm and sit back as up to 1000 tweets are deleted in one go.  If you need to delete more simply repeat the process.

Users do so at their own risk – once tweets are deleted the process can't be undone.