I don't know why these errors keep popping up, I get them myself, and I'm tired to hunting down add ons that either suck, or download links don't work, so I've gotta beg people for the missing file, just to join a server that SUCKS!
With that off my chest. Make sure that the pill is in the right directory as the error message states, as these nooblets don't know how to install add-ons (we need a we to prevent this) because we've got crap from add-ons/add-ons/shapes, and having to redownload the same crap from you personally having it installed correctly.
Anyways, just to repeat myself, just double check that the file is in the right place.
Or as another Blocklander said (along the lines of) "Awoken, sorry, the file is messed up, you'll have to make your own"