Lisp Routine Help Please!!

The routine below is for labelling contours.
I have tried to run the program, but it keeps
coming up with an error after the "digitize a point
to the right" command. AutoCAD returns this message
"error: bad argument type: numberp: nil". Also,
is it possible to modify the program to be able to
automatically pick the z value of the pline in stead
of manually entering the text?? Any help would be greatly appreciated!!!

Al

;*******CONTOUR ELEVATION LABELING ROUTINE******
; ENT - Contour line being labeled
; IPT - Left insertion point of label
; ANG - Insertion angle of label
; DST - Distance to break contour line
; EL - Elevation of selected contour
;-----------------------------------------------
(defun C:CTEXT (/ ENT IPT ANG DST EL)
;-----INITILAIZE PROGRAM----
(setq VARLST (list "OSMODE" "CLAYER" "TEXTSTYLE"))
(start)
(setvar "OSMODE" 512)
(setvar "FLATLAND" 0)
(setq ENT (entsel "\nDigitize the left insertion point: ")
IPT (cadr ENT)
ENT (car ENT))
(setvar "OSMODE" 0)
;-----GET ANGLE & ELEVATION---------
(setq ANG (getangle IPT "\nDigitize a point to the right: ")
EL (rtos (cadddr (assoc 10 (entget ENT))) 2 0))
;----BREAK THE LINE----------------
(setq DST (* SF (* (strlen EL) 0.10)))
(command "break" ENT IPT (polar IPT ANG DST))
;-----------------INSERT THE TEXT------------------------
(command "layer" "m" "TXT100" "")
(command "text" "s" "VLEROY" "m" (polar IPT ANG (/ DST 2))
(* SF 0.1) (angtos ANG 0 4) EL)
(done)
)

 

In below sequence: The variable 'SF' is not being set.
----------------------------
(setq ENT (entsel "\nDigitize the left insertion point: ")
IPT (cadr ENT)
ENT (car ENT))
(setvar "OSMODE" 0)
;-----GET ANGLE & ELEVATION---------
(setq ANG (getangle IPT "\nDigitize a point to the right: ")
EL (rtos (cadddr (assoc 10 (entget ENT))) 2 0))
;----BREAK THE LINE----------------
(setq DST (* SF (* (strlen EL) 0.10)))
-------------------------

You may want to add:
(setq SF (getvar "DIMSCALE"))
Just after:
(setvar "OSMODE" 0)

Bob

 

What kind of object are you selecting at the "digitize a point to the right"
prompt?
___

 

I don't know what (start) does, but SF is not set. That is causing the
error.
This version will pick the z value from the first point selected.

(defun C:CTEXT (/ ENT IPT ANG DST EL)
;-----INITILAIZE PROGRAM----
(setq VARLST (list "OSMODE" "CLAYER" "TEXTSTYLE"))
;(start)
(setvar "OSMODE" 512)
(setvar "FLATLAND" 0)
;(setq ENT (entsel "\nDigitize the left insertion point: "))
;(setq IPT (cadr ENT))
(setq
IPT (getpoint "\nDigitize the left insertion point: ")
ENT (car (nentselp IPT))
)
(setvar "OSMODE" 0)
;-----GET ANGLE & ELEVATION---------
;(setq SPT (getpoint "\nDigitize a point to the right: "))
(setq ANG (getangle IPT "\nDigitize a point to the right: "))
(setq EL (rtos (caddr IPT) 2 0))
;----BREAK THE LINE----------------
(setq DST (* SF (* (strlen EL) 0.10)))
(command "break" ENT IPT (polar IPT ANG DST))
;-----------------INSERT THE TEXT------------------------
(command "layer" "m" "TXT100" "")
(command "text" "s" "VLEROY" "m" (polar IPT ANG (/ DST 2)) (* SF 0.1)
(angtos ANG 0 4) EL)
;(done)
)

 

I am selecting a point along the same contour.