My computer is smarter than me. How do you make the pictures bigger?

Okay, how to you set it up so that someone can click on a picture in your blogspot - and it opens a larger version of the picture in a new window??? I used to be able to do this - without doing anything. It just did it automatically. I seemed to have lost that superhuman ability. Sometimes it works and sometimes it doesn't. Watch - in this post, when you click on the picture it will open a new window. That's because the Blogger-Powers-That-Be want to make me look like an idiot. Most of the time, when you click on pictures in my posts, nothing happens (for example, the pictures in my post about Kurt). What have I done to deserve such blog-wrath? More importantly, how do I fix it?