they just do n't work in concert . 
(ROOT (S (NP (PRP they)) (ADVP (RB just)) (VP (VBP do) (RB n't) (VP (VB work) (PP (IN in) (NP (NN concert))))) (. .)))
(ROOT (S (NP (PRP )) (ADVP (RB )) (VP (VBP ) (RB ) (VP (VB ) (PP (IN ) (NP (NN ))))) (. )))