Ubuntu :: Find Execdir Convert -resize "find: Missing Argument To `-execdir'"

i'm trying to resize my album art that is dispersed through various artist/album folders. They are mostly 200x200, but i want to make all of them the same size. The code i'm trying to use is,

Code:

find -iname "cover.jpg" -execdir convert -resize 200x200 {}

or

Code:

find -iname "cover.jpg" -execdir convert {} -resize 200x200

i'm getting the error,

Code:

find: missing argument to `-execdir'

on both whats wrong with my syntax.