Timeline only shows "Tweets by @" instead of widget


We just placed a twitter timeline widget in our Google Sites webpage to be used in our domain.

The timeline widget shows correctly in Google Sites:


But it only shows “Tweets by @CosmosMataro” in:


What can be the problem?

This is the twitterfeed.xml file we use:

<?xml version="1.0" encoding="UTF-8" ?> <![CDATA[ Tweets por @CosmosMataro ]]>