Do you have a custom favicon designed for your blog or website,you can confirm that it is working fine at http://www.html-kit.com/favicon/validator/
Favicon Validator is a free online service that can be used to validate favicon files, link tags and related items on web pages.
If you’d like to double check the favicon on your web page or if you are having trouble viewing it, enter your web page or blog address at the website above and click “Check”
After some seconds, the result page will load and will tell you the facts about your favicon.
If it doesn’t work for you, you can check out this favicon validator.