Constraining two vectors to be in the same domain but not be member's of each other

I've used clojure for a while but just starting out with core.logic.

Given a domain like 1 2 3 4 I want to get a vector of two vectors back like ([[1 2] [3 4]]).

Note: This is just a simplified version of what I'm really trying to do. :) See: https://github.com/adamhoward/lineup

I found this definition for not-membero on the web:

(defne not-membero [x l]
  ([_ []])
  ([_ [?y . ?r]]
    (!= x ?y)
    (not-membero x ?r)))

And I'm trying to use it like this:

(run 1 [q]
     (fresh [w x
             y z]
            (== q [[w x]
                   [y z]])
            (infd w x y z (domain 1 2 3 4))
            (everyg distinctfd [[w x] [y z]])
            (everyg #(not-membero % [y z]) [w x])))

Running this in Emacs gives me an Evaluation aborted. message.

When I try switching out membero for not-membero I get back ([[1 2] [1 2]]) which makes sense to me. Every element in the first vector [w x] is a member of the second vector [y z].

But, when I call run 2 I get back ([[1 2] [1 2]] [[1 2] [1 3]]). I don't understand how [[1 2] [1 3]] can be correct for the rules above. Am I not understanding everyg correctly? Any guidance (including rtfmanual, rtfbook, rtfdissertation) will be appreciated.

Thanks.

Edit: May have solved this.

Still not sure about the strange results from membero but instead of the not-membero goal I found that I could do this:

(everyg #(distinctfd (conj [y z] %)) [w x])

Each element of [w x] conj'd to [y z] contains all distinct values. This may be less efficient than not-membero so I'm still open to any help.