[R] How to specify arguments in lme() ?

[w jj]

Hi,

I have a question about the function lme() in R.

I have a 2*2*3 layout with some missing data (labelled as *).  These 3 
factors are labelled as A,B,C, the response is Score. The layout is as 
follows:-

A              B                 C                    Score
1               1                  1                         5
1               1                  2                         *
1               1                  3                         1
1               2                  1                         4
1               2                  2                         4
1               2                  3                         *
2               1                  1                         3
2               1                  2                         *
2               1                  3                         4
2               2                  1                         2
2               2                  2                         *
2               2                  3                         5

Suppose these data are stored in a data frame called "test".

If all these 3 factors are fixed, then I can fit a model without the 3-way 
interaction as:-
fit1<-lm(Score~A*B+A*C+B*C,data=test)        

If one of these factors, say A, is a random effect variable, then I need to 
fit a mixed effect model using lme(). I have read the R documention on 
lme(), but I am still not clear how to specify the random argument. I tried 
to do:-

fit2<-lme(Score~A*B+A*C+B*C,data=test,random=~A, na.action=na.pass) 

but the system give a message as follows:-
Error in getGroups.data.frame(dataMix, groups) : 
        Invalid formula for groups

So how should I specify the arguments? 

Thank you very much for your help!

Jiajie