That particular folder isn't meant for you to drag to. that's where the OS puts its services that all users use.
you should put it in /Library/Services/ (create if needed) or in (home)/Library/Services/ (create if needed)
The former is for all users to use, but does not contain services made by the OS, and the latter is only for your user to use.
Would not surprise me if a restart is required for it to "see" new services.
