@name only works if you use the login name of the poster. For example, Catman's login name is catman56, so @catman56 will create a tag for him. If you look at the poster's info next to a post, you can see the login name right above the post count.
You can also use the tag tool to insert a name. On the tool bar, it's the one left of the big C and right of the movie clapboard. Once you open the tool, just type in the name of interest, and it will zero in on names close to what you type. When you see the one you want, click on it, and the proper code will be placed.
When you're a Cat, You're a Cat all the way From your first catnip mouse To your ninth dyin' day.