R help - Sep 2003 - lmList with NAs

Hello R-Helpers, 
 
I was trying to use the lmList function to get the lmList graphic similar to
Pinheiro and Bates (pg 33).  I did not have a problem creating the graphic when
I used the Orthodont data frame or 2 other data sets when there are no missing
values.
My data has missing values.  Do I need to remove the missing values before the
lmList function will work?
 
for a small example:
> a
  schoolid spring score childid
1        1      0   550     345
2        1      1   568     345
3        1      0   560     456
4        1      1    NA     456
5        2      0   540      32
6        2      1   562      32
7        2      0   579      34
8        2      1   599      34
> a1=groupedData(score~spring|schoolid,data=a)
> a1try=lmList(a1,na.action=F)
Error in lmList.formula(object = score ~ spring, na.action = F, data = a1) : 
        data must be a groupedData object if groups argument is missing 
 
# problem also occurs when I do not use groupedData statement .  
 
 > atry<-lmList(score~spring|schoolid, data=a)
Error in na.fail.default(data) : missing values in object
 
 > atry<-lmList(score~spring|schoolid, data=a,na.action=F)
Error in getGroups(data, form = grpForm, level = level) : 
        no applicable method for "getGroups"
 
#don't know what I should do now. 
 
 Any help would be greatly appreciated.  
 
(R1.7.1 for Windows)
 
Thank you, 
Tami Hoffman 

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