Post link not active on Home but is active on Post

Somewhat new to WordPress and can’t seem to make a link work on any Posts on the Home Page. See “Testing” topic at top:

http://blog.greenmuseum.org/greenhousebritain/

If I click on the Post itself the link is live and works fine:

http://blog.greenmuseum.org/greenhousebritain/?p=19

If I go back to the Home page, it’s dead. Tried, refreshing & reformatting the link and checking all my settings and no progress. Any clue what’s going on or how to fix this?

Thanks!