Why are my 'Latest Tweets' not showing on my website?

This problem may occur when your latest tweet is a retweet*, or when your account has been rate limited.

Retweet Issue

If your latest tweet is a retweet it will not show on your website.  For some reason known only to Twitter, retweets are not currently included in Twitter's feed service. This is a known problem that Twitter is working on (we can only hope!) .

Twitter Rate Limiting

Twitter places a limit on the number of times you can view tweets from a particular account externally to their own website (via calls to their API).  This limit is currently set to 150. When this limit is exceeded you will no longer be able to view your twitter feeds from your computer (and probably other computers in your office if you are using a shared IP).

Why does Twitter have this limit?

The limit was introduced by Twitter to reduce the load on their servers caused by the recent increase in traffic from external sites using their API, and is intended to encourage more efficient usage of their API.
 

*A retweet is when you see a Tweet written by someone else that you would like to share with your followers. For more information on retweeting see http://support.twitter.com/entries/77606-what-is-retweet-rt