R help - Feb 2007 - Multiple comparisons

Dear list,

I have to do an ANOVA analysis with one fixed effect A and one random 
effect SUBJECT. TO do this I used aov in the form
 > aov.m1 <- aov(depvar ~ A + Error(SUBJECT/(A)));

My question is if I obtain significant differences within the strata, 
does it make any sense to make multiple comparisons in order to know 
what levels of the factor are significant?. I asked this because I get 
an error when I try

TukeyHSD(aov.m1), and I am not sure if this is correct.

thanks

Pablo Hoffmann

Dear "R" users,
I need a professional help:

i am a relatively new "R" user and I am just writing my diploma tesis
where I have to conduct some multiple comparison.
I am searching a method which include interaction between fixed factors. The
following is my model:
lmer(Leaf~water*region+(1|pop)+(1|pop:sib)+(1|block)+(1|block:pool),data=datx,method="ML")
I want to compare: leaf dependent from water * region.

I would prefer to make a comparision according to tukey or student newman keuls
if this is possible.
I am looking forward to your reply, sincerely Petra:-)