fintancostello - 2:14 pm on Mar 30, 2010 (gmt 0)
As you are a new Twitter user and as I cannot see your account, I'm going to take a guess and say you might be looking at it wrong.
When you log into twitter you get taken too:
Which will show tweets of people you follow, so if you are not following anyone you will get "no tweets"
To see tweets you have made you need to click on "profile" and you will be taken to [twitter.com...] from here you will see the tweets you have made.
Or as others have said, sometime Twitter makes mistakes :)