You would think putting a Twitter Feed on the side of your blog would be relatively easy, but speaking from experience, IT'S NOT. I spent several hours following different "walk-throughs," but in the end, nothing worked.
The easy part was putting the Twitter "Button" on the blog. I simply went to http://twitter.com/badges/ and followed the self-explanatory instructions. After a few seconds, Twitter redirected me to Blogger where I OK'd the placing of the Twitter button on the blog. Viola! My site was now pulling Twitter posts as it promised... or had it.
But here's where things got messy.
The thing that gave me the most trouble was that feed would not pull MY Twitter feeds, but other random Twitter feeds (perhaps it wasn't truly random, but there was no discernible pattern to me).
Next, I began to reason my way through the code. I first noticed the above highlighted word: "Undefined." Now I'm no script-kiddie, but I'm pretty sure that the word "Undefined" should not show up in a script.
I proceeded to exchange both of the "Undefined"s for "Twitfellow" (my Twitter Username). Then I crossed my fingers... and refreshed the page... and BAM! Worked like a charm.
Hope this was helpful to all you other bloggers who are having trouble.
Please leave me feedback, too. Oh yea, and join my Tweets!