Create Nested Toggle (Check) Boxes

Hello,

I am new to SKILL and would like to take your inputs on the below scenario.
I am creating a App form with Toggle (Check) Boxes for few lines in a file which are as below:

 <file lout >
Numbers
1,2,3,4,5
6,7,8,9,10
11,12,13,14,15

Characters
a,b,c,d,e
e,f,g,h,i
j,k,l,m,n

Letters
ab,cd,ef,gh,ij
kl,mn,op,qr,st


I read each line from file lout and create a Check Box for each line but if the user selects “Numbers” or “Characters” then all lines below “Numbers” or “Characters” must be checked until an empty line is read.
I have the below code which errors out with below message:

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*Error* hiCreateToggleField: each toggle item must be a list of at least it's unquoted symbol representation
*Error* load: error while loading file - "te.il"
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 Can you please help me with the error check on this code as I am not familiar with most SKILL functions . Thanks in advance.
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CODE
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procedure(readcsv(ln)
 cline=ln
 tline = substring(cline 1 strlen(cline)-1)
 pline=parseString(tline ",")
  i=length(pline)
;  printf("Length is %d\n" i)
   item8 = nth(i-1 pline)
   item7 = nth(i-2 pline)
   item6 = nth(i-3 pline)
   item5 = nth(i-4 pline)
   item4 = nth(i-5 pline)
;printf("ITEM'S 1-8:\n %L\n %L\n %L\n %L\n %L\n %L\n %L\n %L\n" item1 item2 item3 item4 item5 item6 item7 item8)
lista = list(item4 item5 item6 item7 item8)
printf("LIST ITEM'S:%L\n" lista)
lista
);end proc readcsv


port=infile("lout")
listN='()
listM='()
listNew='()
count =0
when(port
   while(gets(ln port)
        listb=readcsv(ln)
        listM = cons(listb listM)
        ;printf("ListM:%L\n" listM)
    );end while
   );end when
 close(port)

; Create Check Box

mytoggle = hiCreateToggleField(
 ?name ’toppings
 ?prompt "Toppings"
 ?choices listM
 ;?value ’( nil)
 ;?numSelect 1 )
)
hiCreateAppForm( ?name ’iceCreamForm
 ?formTitle "Ice Cream"
 ?callback "buildIceCreamCone()"
 ?fields list( mytoggle )
 ?help "cream" )
status = hiDisplayForm( iceCreamForm )

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