I have tried to Follow another couple of wordpress.com blogs by clicking Follow. This is one: http://thebuggeek.com
The box comes up and I fill in the email address I use with my wordpress.com account. This used to work (I think something has changed; I don't remember having to fill in my email address).
This results in this message:
"Your subscription did not succeed, please try again with a valid email address.
You can now manage the blogs you follow in the Reader on the WordPress.com home page."
There was another post that said something about username not being linked with the primary blog, but mine already is.
The blog I need help with is moonlittrails.wordpress.com.