[R] Multiple comparisons

[Pablo Faundez Hoffmann]

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