rename all directories below top level

It seems like this should be a really easy function to do, however I cannot figure out how to accomplish this.

I have a top level directory with many sub directories. There are probably hundreds of nested folders going down 3,4,5 levels deep.

I have my method added, and the directory ... but it appears the application does not automatically traverse all the directories down to each lowest path.

Anyone know how to accomplish this?

---