Understanding the usage of #tag - not grouping as expected

[cdsaenz]

I'm trying to organize my gists according to programming language used. From what I've read I might use a repository but I might like to stick to gists if possible. I think the tag solution mentioned in #7 would be great, to create a "virtual folder" by language or project. But somehow I cannot make it work. Must be something silly I'm doing. Screenshot below of what I attempted: the tag sticks to the description but doesn't create a branch in the tree. Thanks a lot!