Multi-filter error: void-function nil

Hi again,

unfortunately I have again a problem with the filter system.

Let's say I want to filter works by 3 musicians: Guédron, Boêsset and 
Moulinié. If I create the filter manually (push-or, etc.) it works 
wonderfully.

If I keep the filter I get the following:

("Multi-filter"
  "Artist : (moulinié)  | Artist : (guédron)  | Artist : (boesset) "
  (("Artist : (moulinié)" "Artist : (guédron)" "Artist : (boesset)")))

If I copy this code to my config with something like this:

(setq general-filters
       '(("Multi-filter"
          "Renaissance: Air de cour"
          (("Artist : (guédron)" "Artist : (boesset)" "Artist: 
(moulinié)")))))

(emms-filters-make-filters general-filters)
(emms-filters-add-to-filter-menu-from-filter-list "Propios" general-filters)

I get the following error: Lisp error: (void-function nil)
And the whole backtrace: https://paste.debian.net/1412120/

Any ideas?

Thanks in advance.

Best,

PS: If I define filters with the Artist factory for every composer and 
create then a multi-filter like so:

(setq probando-filters
       '(
         ("Artist" "Guédron"  "guédron")
         ("Artist" "Boesset" "boesset")
         ("Artist" "Moulinié" "moulinié")

         ("Multi-filter"
          "Air de cour"
          (("Guédron" "Boesset" "Moulinié")))))

Then it works without problems...