LISP: To few arguments error

Probably a simple question from a lisp newbie:

I am working with two routines I downloaded from

4d-technologies.com

The routines should label a 3Dpoly with an arrow drawn from High to Low indicating the direction water would flow.

When I try and run the routine it gives me the following error:

Command: pl_drawleaders
*Cancel*
too few arguments

I have both routines loaded into autocad.

;; ! ****************************************************************************
;; ! PL_DrawLeaders
;; ! ****************************************************************************
;; ! Function : Draws Leaders along each segment of the polyline, thus showing
;; ! the direction of flow of the polyline.
;; ! Arguments:
;; ! 'vlist' - List of coordinates of the polyline
;; ! 'Closed' - Flag to indicate if the polyline is closed or not
;; ! Action : Returns a selection set of all the leader objects created
;; ! Updated : November 11, 2000
;; ! Copyright: (C) 2000, Four Dimension Technologies,

(defun cL_DrawLeaders( vlist Closed / Seg SegLst ss OS )

(setq OS (getvar "OSMODE"))

(setvar "OSMODE" 0)

(setq ss (ssget))

(setq
SegLst (GE_GetSegmentPoints vlist Closed)
ss (ssadd)
)
(foreach Seg SegLst
(command "._Leader" (nth 1 Seg) (nth 0 Seg) "" "" "_None")
(ssadd (entlast) ss)

)
(setvar "OSMODE" OS)
(if (> (sslength ss) 0) ss nil)
)

Routine # 2:

;; ! ****************************************************************************
;; ! GE_GetSegmentPoints
;; ! ****************************************************************************
;; ! Function : Returns a list of all segment start and end points from a list
;; ! of points
;; ! Arguments:
;; ! 'vlist' - List of points
;; ! 'Closed' - Flag to indicate if the polygon is closed
;; ! Action : Returns a list of segment points
;; ! Updated : February 8, 1999

(defun c:GE_GetSegmentPoints( vlist Closed / SegPtLst cnt len pt1 pt2 )
(setq SegPtLst '())
(if vlist
(progn
(setq
len (length vlist)
cnt 0
)
(repeat (1- len)
(setq
pt1 (nth cnt vlist)
pt2 (nth (1+ cnt) vlist)
SegPtLst (cons (list pt1 pt2) SegPtLst)
cnt (1+ cnt)
)
)
(if Closed
(setq SegPtLst (cons (list (last vlist) (car vlist)) SegPtLst))
)
(setq SegPtLst (reverse SegPtLst))
))
SegPtLst
)

Thanks in advance,

Scott