R help - Oct 2007 - (no subject)

Can anybody explain me what does it mean "Estimated effects may be  
unbalanced", and what does it imply for the anova analysis?

Here a case example of what I get.

 > D<-expand.grid(A=c(0,1,2,3),B=c(0,1),C=c(0,1),res=c(runif(30,0,1)))
 > aov(res~A*B*C,data=D)
Call:
    aov(formula = res ~ A * B * C, data = D)

Terms:
                        A        B        C      A:B      A:C       
B:C    A:B:C Residuals
Sum of Squares   0.00000  0.00000  0.00000  0.00000  0.00000   
0.00000  0.00000  50.93402
Deg. of Freedom        1        1        1        1        1         
1        1       472

Residual standard error: 0.3284982
Estimated effects may be unbalanced

Thanks in advance


PS: > R.Version()
$platform
[1] "powerpc-apple-darwin8.10.1"

$arch
[1] "powerpc"

$os
[1] "darwin8.10.1"

$system
[1] "powerpc, darwin8.10.1"

$status
[1] ""

$major
[1] "2"

$minor
[1] "6.0"

$year
[1] "2007"

$month
[1] "10"

$day
[1] "03"

$`svn rev`
[1] "43063"

$language
[1] "R"

$version.string
[1] "R version 2.6.0 (2007-10-03)"


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Max MANFRIN                                 Tel.: +32 (0)2 650 3168
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