I am having the same problem. I use an online tool to create my website which allows to add HTML elements in it. I had never a problem with any HTML code I embeded or pasted there, but when I paste yours I get only the display text “Tweets by @icelma86” and nothing else.
I tryied if the code would work at the HTML Trial Editor from w3schools.com to check if it would work with them and I get the same text or error that I get with the website editor.
I tried this with all the widgets (conversation, favorites, lists, search) and none of them are working. What should I do?