Found this a problem with Acad 2015 - if you get this error go into your code and look for 'mapcar' then within that look for 'command' and change to 'command-s'
(if plst
(progn
(mapcar
'(lambda (X)
;turn layer on
(if (> (cadr X) 0)
(command-s "._-LAYER" "_ON" (car...